ShipModul MiniPlex-3USB, MiniPlex-3USB-N2K, MiniPlex-3E, MiniPlex-3E-N2K User guide

MiniPlex-3 series NMEA 0183/2000 multiplexer

Manual

This manual covers:

MiniPlex-3USB

MiniPlex-3USB-N2K

MiniPlex-3E

MiniPlex-3E-N2K

MiniPlex-3 series, V1.0

Firmware V1.0.x/1.9.x
Rev. C, 11-9-2015

© CustomWare, 2015

2

Introduction ................................................................................................................................ 4!

NMEA 0183 ................................................................................................................................. 4!

NMEA Sentences ....................................................................................................................... 4!

Talkers and Listeners ................................................................................................................ 4!

The Multiplexer ......................................................................................................................... 5!

The Host .................................................................................................................................. 5!

The MiniPlex-3 Multiplexer ......................................................................................................... 6!

Galvanic Isolation ................................................................................................................... 6!

NMEA 2000 ........................................................................................................................... 6!

Feature Set ........................................................................................................................... 6!

Host Port .................................................................................................................................... 8!

USB Port .................................................................................................................................... 8!

Driver Installation .................................................................................................................. 9!

Network Interface ...................................................................................................................... 14!

Network Basics ....................................................................................................................... 14!

IP Address .......................................................................................................................... 14!

Netmask ............................................................................................................................. 14!

Port Number ........................................................................................................................ 14!

Protocols ............................................................................................................................. 15!

Assigning IP addresses ............................................................................................................ 15!

MiniPlex-3E Network Setup ...................................................................................................... 16!

Search ................................................................................................................................ 17!

Network Recovery ................................................................................................................ 18!

NMEA 0183 Ports ....................................................................................................................... 19!

NMEA 0183 Signals ................................................................................................................. 19!

NMEA 0183 Inputs .................................................................................................................. 19!

NMEA 0183 Outputs ................................................................................................................ 20!

Combining Ports ..................................................................................................................... 21!

SeaTalk ................................................................................................................................. 21!

NMEA 2000 ............................................................................................................................... 22!

Connecting to the NMEA 2000 network ...................................................................................... 23!

Power Supply ............................................................................................................................ 24!

Indicators ................................................................................................................................. 24!

Data Throughput ....................................................................................................................... 25!

MPX-Config-3 ............................................................................................................................ 27!

Menu .................................................................................................................................... 28!

Controls ................................................................................................................................ 29!

MiniPlex Connection .............................................................................................................. 29!

Viewer Options .................................................................................................................... 30!

NMEA Inputs/Outputs ........................................................................................................... 31!

Options ............................................................................................................................... 34!

NMEA Conversions ............................................................................................................... 35!

Wind: VWR <-> MWV ........................................................................................................... 36!

Sentence Filtering & Routing .................................................................................................. 37!

NMEA 2000 ......................................................................................................................... 40!

Firmware Update ....................................................................................................................... 41!

Procedure .............................................................................................................................. 41!

Mounting .................................................................................................................................. 42!

Technical Reference ................................................................................................................... 43!

NMEA 0183 Glossary ............................................................................................................... 43!

Talker ID’s .......................................................................................................................... 43!

Sentence formatters ............................................................................................................. 43!

Supported NMEA 2000 PGN’s .................................................................................................... 45!

Translated SeaTalk datagrams .................................................................................................. 46!

Firmware Update Error messages .............................................................................................. 47!

Standard NMEA 0183 Sentences ............................................................................................... 48!

$MXSTN – Multiple Data ID ................................................................................................... 48!

$MXPGN – NMEA 2000 PGN Data ........................................................................................... 48!

Proprietary NMEA 0183 Sentences ............................................................................................ 50!

Example ............................................................................................................................. 50!

$PSMDC – Get Configuration record ........................................................................................ 51!

$PSMDN – Set NMEA 2000 Configuration ................................................................................. 51!

$PSMDCF – Set Configuration ................................................................................................ 51!

$PSMDDR – Set Default Route ............................................................................................... 51!

$PSMDFL – Set Filter Rules .................................................................................................... 52!

$PSMDID – Set Talker ID ...................................................................................................... 53!

3

$PSMDIN – Input options ...................................................................................................... 54!

$PSMDLDR – Loader message ................................................................................................ 54!

$PSMDOP – Set Options ........................................................................................................ 55!

$PSMDOV – Overflow ........................................................................................................... 56!

$PSMDRESET – Reset the multiplexer ..................................................................................... 56!

$PSMDSP – Set Speed .......................................................................................................... 56!

TAG Block ........................................................................................................................... 57!

$PSMDUI – Set Unique Identifier ............................................................................................ 57!

$PSMDVER – Get Version ...................................................................................................... 57!

Technical Specifications ........................................................................................................... 58!

MiniPlex-3USB ..................................................................................................................... 58!

MiniPlex-3USB-N2K .............................................................................................................. 58!

MiniPlex-3E ......................................................................................................................... 59!

MiniPlex-3E-N2K .................................................................................................................. 59!

4

Introduction

The MiniPlex-3 series NMEA multiplexers enable the connection of multiple NMEA 0183/2000 devices and
a host device like a PC, a laptop or a tablet. All models share the same number of NMEA ports and
features. They differ in the type of host interface, the interface that talks to the computer. Some models
also have an NMEA 2000 interface.

This manual covers all models of the MiniPlex-3 series. There is a chapter for each type of host port. The
remaining part of the manual covers NMEA 0183 connections and configuration, which are the same for
all models.

We will also explain NMEA 0183 and how things connect (or not).

For all –N2K model there’s a chapter about NMEA 2000.

NMEA 0183

The NMEA 0183 Standard, a communication standard defined by the NMEA organization
(www.nmea.org), defines a communication protocol called NMEA 0183 that enables navigation
instruments and devices to exchange data with each other.

This way, a compass can send a heading to a radar to enable a north-up display, a GPS can send cross­track and waypoint information to an autopilot in order to steer a programmed course.

NMEA Sentences

NMEA data is made up of readable text sentences. If you would connect the output of a navigation
instrument to the serial port of a computer and start a program that displays the incoming data, you
would see something like this:

$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*2E

$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*39

$GPGLL,5301.0061,N,00635.5479,E,143357.999,A*22

$HEHDT,67.0,T*1E

This is plain text in a format that is laid out in the NMEA 0183 standard. Every device that receives this
information would know that the sentence starting with GPGLL originates from a GPS (hence the GP at
the beginning of the sentence) and that it contains the geographic longitude and latitude (GLL).

The term “NMEA sentence” is used for NMEA data because it is made up of single lines of text.
Throughout this manual, “NMEA sentences” and “NMEA data” will be used randomly.

Talkers and Listeners

The NMEA 0183 standard defines talkers and listeners. A device that sends information is a talker and a
device that receives information is a listener. When connected to each other, the talker sends information
to the listener.

Communication using the NMEA 0183 protocol involves at least one talker
sending data to one listener. Figure 1 on the right shows such a minimal
system: a gyrocompass sends heading data to a radar.

It is important to know that a talker or listener port is named after its
function, not after what it is connected to. So a talker port sends out
information but it connects to a listener. This might be confusing at times so further in this manual we
will use the terms input and output instead of listener and talker port respectively.

The NMEA 0183 standard specifies that a talker should have enough driving capacity to talk to four
listeners. This is as easy to achieve as telling a story to an audience of four people - the only requirement
is to talk loud enough.

Gyro Radar

Figure 1

5

Figure 2

The left part of Figure 2 shows such a situation: one GPS sends data to four devices.

It gets complicated when several talkers must send data to one listener (the PC) as shown in the right
part of Figure 2. Unless that listener has multiple inputs, this is not possible without help.

Simply connecting multiple talkers to one listener as shown is like four people simultaneously telling you
a different story. You can make neither head nor tail of it. In electronics terms: the outputs of the talkers
will short-circuit each other and the sentences they transmit will be corrupted.

This is where a multiplexer offers the solution.

The Multiplexer

A multiplexer, sometimes called combiner, has multiple listener
ports, each acting as a listener connected to a single talker. It also
has at least one talker port that outputs the combined data from
the inputs to a listener. So what seemed impossible in Figure 2 is
possible when a multiplexer is added as shown in Figure 3. The
multiplexer listens to the instruments by storing the received
NMEA sentences into queues simultaneously. At the same time it
retrieves the sentences from the queues sequentially and sends
them to the PC.

Since a PC can do so much more than just displaying the
combined data, it soon became apparent that a multiplexer needs
more than just a few inputs and one output. The single talker port
that connects to the PC became a host port, being input and
output at the same time. A few extra talker ports made it possible
to send data to other devices and to drive an autopilot.

The Host

NMEA 0183 devices already existed before it was common practice to use a computer for navigation. Of
course there were ECDIS systems (Electronic Charting and DISplay) but these were used only on
commercial ships. Nowadays it is very common to use a computer, a laptop or a tablet as a charting
device while the navigation software sends information to an autopilot in order to automatically follow a
programmed route. This computer, laptop or tablet becomes a navigation host and what used to be a
talker port on the multiplexer is now called a host port. The multiplexer becomes the central interface
that listens and talks to all navigation instruments and devices.

Throughout this manual, the common term Host is used for a PC, laptop, smartphone, PDA, tablet or any
device that is connected to the multiplexer to send and receive NMEA data for processing and display.

The host interface or host port is the interface that connects to these devices and this can be a USB,
Ethernet or WiFi interface.

GPS

PC

VHF

Radar

Auto-

pilot

PC

GPS

Depth

Wind

Log

PC

GPS

Depth

Wind

Log

Multiplexer

Figure 3

6

The MiniPlex-3 Multiplexer

The MiniPlex-3 multiplexer is an advanced NMEA 0183 multiplexer with four NMEA inputs or listener
ports, two NMEA outputs or talker ports and one or two host interfaces.

It combines NMEA sentences that are received on the NMEA
inputs and it can send these sentences to the NMEA outputs
and to the host interface(s). These host interfaces can also
be used to send NMEA sentences back to the multiplexer to
be forwarded to its NMEA outputs and to send commands to
configure the multiplexer.

Figure 4 shows a typical setup where the MiniPlex-3 is used
to combine data from four instruments, send it to a PC and,
depending on the configuration of the MiniPlex, send the
same data to an autopilot and a repeater display. The PC is
also capable of controlling the autopilot to steer a
programmed route and to display information such as
distance to next waypoint on the repeater display.

Galvanic Isolation

Every NMEA input and output of the MiniPlex-3 is galvanically
isolated, sometimes called opto-isolation because opto-couplers are used to achieve this isolation. An
opto-coupler is an electronic component that transports information by means of light instead of
electricity, thus creating a barrier for electrical currents and voltages.

Galvanically isolated inputs and outputs prevent unwanted flow of electrical currents between instruments
and the multiplexer. These currents could damage the instruments or interfere with radio signals and
should therefore be avoided. Galvanically isolated inputs are required by the NMEA 0183 standard. As an
extra measure of protection, the MiniPlex-3 also has galvanically isolated outputs.

The host port or interface of the MiniPlex is also galvanically isolated in order to isolate the host from the
navigation network and protect it against potential damage caused by ground loops or voltage spikes.

Both NMEA outputs can drive up to four listeners each. Flexible routing options allow you to specify which
NMEA sentences are sent to these outputs. The outputs are also galvanically isolated. The NMEA 0183
standard does not require this but we added isolation because it makes the outputs more universal when
it comes to connecting them to different kinds of inputs (NMEA 0183/RS-422 or RS-232).

NMEA 2000

Some models in the MiniPlex-3 range (the ones
ending on ‘-N2K’) are equipped with an NMEA 2000
interface to connect to an NMEA 2000 backbone with
other navigation instruments. The MiniPlex-3 will
translate NMEA 2000 PGN’s (messages) into NMEA
0183 sentences and vice versa. This feature enables
a seamless integration between NMEA 0183 and
NMEA 2000 navigation devices. It also allows
navigation software, which usually only supports
NMEA 0183, to receive data from NMEA 2000
devices and to control NMEA 2000 autopilots. Figure
5 shows a typical setup, which makes the data from
the GPS/plotter available to the PC and a repeater.
Similarly, the data from the Depth, Wind and Log
instruments and the PC will be sent onto the NMEA
2000 backbone for use by the GPS/plotter and the
autopilot.

Feature Set

Besides the basic functionality of combining NMEA
sentences from multiple sources, the MiniPlex-3

offers a range of features like sentence filtering and
routing, input priority with automatic switchover,
testing of data integrity, NMEA 0183 conversions, Talker ID modification and SeaTalk® to NMEA
translation.

The MiniPlex-3 can be integrated seamlessly into an existing Raymarine SeaTalk network when SeaTalk
mode is enabled. This mode changes one NMEA input into a SeaTalk input. When connected to a

Figure 4

PCGPS

Depth

Wind

Log

MiniPlex-3

In1

In2

In3

In4

Out1

Out2

Host

Autopilot

Repeater

PC

Depth

Wind

Log

GPS/

Plotter

MiniPlex-3-N2K

In1

In2

In3

In4

Out1

Out2

Host

Autopilot

Repeater

NMEA 2000

NMEA 2000 Backbone

Figure 5

7

Raymarine SeaTalk network, the multiplexer translates SeaTalk data into NMEA sentences and combines
these with NMEA sentences that are received on the other inputs. Only one SeaTalk input is needed since
the SeaTalk bus connects all instruments together through one single cable.

SeaTalk to NMEA translation in the MiniPlex works one-way only: no NMEA sentences are converted into
SeaTalk, the multiplexer just listens on the SeaTalk bus.

All MiniPlex-3 models have the same features and number of NMEA inputs and outputs. The only
difference between each model is the type of host port. The following chapters describe the details of
each host port.

8

Host Port

The host port is the port that connects to a PC, laptop, smartphone, PDA, tablet or any device that is
connected to the multiplexer to receive the combined NMEA data for processing and display. The type of
host port differs for each type of multiplexer.

The host port is always bi-directional: it delivers the combined NMEA 0183/2000/SeaTalk data from the
multiplexer to the host and it also receives NMEA data from the host to be sent to the NMEA outputs of
the multiplexer. The host port is also used to configure the multiplexer and to update its firmware.

The following chapters describe each type of host port. The applicable type of multiplexer is listed
underneath the caption.

USB Port

(MiniPlex-3USB, MiniPlex-3USB-N2K)

The USB port is galvanically isolated from the multiplexer to prevent ground loops when connected to a
computer. Ground loops can result in excessive currents in ground connections, which could destroy the
multiplexer or the serial port of the connected computer.

Because of this galvanic isolation, a MiniPlex-3 with a USB port will not be powered from the USB bus
unlike older MiniPlex models. The MiniPlex-3 always requires a separate power supply to operate. The
USB port however does receive its power from the USB bus. A computer will therefore always show a
virtual COM port when the multiplexer is connected, with or without power supply.

The USB port supports flow control. Flow control is needed when waypoints and routes or other larger
amounts of data are sent from the computer to the multiplexer. The communication speed of the USB
interface is 10 to 100 times higher than an NMEA 0183 output. This causes the internal buffers in the
multiplexer to fill very rapidly, causing the multiplexer to drop sentences.

Flow control prevents this from happening. When the buffers in the multiplexer are almost filled up, the
multiplexer signals the computer to stop sending data. When the buffers are sufficiently emptied, the
multiplexer signals the computer to continue. This requires a special setting in your navigation software,
which is called “flow control” or “handshake”. This setting can mostly be found in the port settings of your
software.

Set the flow control to “Hardware” or “CTS/RTS”. Do not use “Xon/Xoff” flow control since this uses
special characters instead of a signal. These characters are not part of the NMEA standard and therefore
not supported by the multiplexer.

9

Driver Installation

To use a MiniPlex-3 with a USB port, a driver must be
installed. This driver creates a virtual COM port, which
can be opened by navigation software.

The CD contains drivers for Microsoft Windows
(Windows 2000, XP, Vista, 7, 8 and 10) and Apple’s
Mac OS X.

Windows 7 and up

When the MiniPlex is connected to the computer for
the first time, Windows will automatically download
the most recent drivers from the Windows Update
Service if an Internet connection is available. Without
Internet connection, these drivers must be installed
manually.

To install the drivers for the MiniPlex manually, open
the Control Panel, choose “System and Security” and
then “Device Manager”.

The Device Manager will show a “ShipModul MiniPlex­3USB” listed under “Other Devices” as shown in Figure

6.

Right-click on the MiniPlex entry and choose “Update Driver Software...” from the menu that appears.
This will open the window as shown in Figure 7.

Choose “Browse my computer for driver
software”.

Figure 7

Figure 6

10

A new window opens (Figure 8) where
you must choose the location of the
driver. The driver is located in the
subfolder “\USB Driver\Windows” on the
MiniPlex Driver & Utility CD.

If you click on “Next”, Windows will
install the driver.

When Windows has successfully installed
the driver, the window as shown in
Figure 9 appears.

You can close this window.

Figure 8

Figure 9

11

The Device Manager will now list a “USB Serial Port”
under “Other Devices” (Figure 10). For this port to work,
a second driver needs to be installed.

Right-click on the USB Serial Port entry and choose
“Update Driver Software...” from the menu that
appears. This will open the window as shown in Figure

11.

Choose “Browse my computer for driver
software”.

Figure 11

Figure 10

12

A new window opens (Figure 12) where
you must choose the location of the
driver again. This time, the location is
already set and you can click on “Next”.

When Windows has successfully installed
the driver, the window as shown in
Figure 13 appears.

You can close this window.

The Device Manager will now list a “ShipModul MiniPlex
NMEA Multiplexer” under “Universal Serial Bus
controllers” and a “MiniPlex-3 Serial Port (COMx)” under
“Ports (COM & LPT)”.

Figure 12

Figure 13

Figure 14

13

Windows XP

When the multiplexer is connected to a USB port for the first time, Windows will detect new hardware
and prompts you for a driver. Insert the supplied CD into the drive and follow the instructions on your
screen. If you have an Internet connection, you can let Windows search the Internet for updated drivers.
Otherwise, when asked to automatically search for drivers, answer no and choose the option to tell
Windows where to find the driver. The driver can be found on the supplied CD, in de folder “\USB
Driver\Windows”

The installation on Windows is a two-step process. First, the driver for the multiplexer will be installed.
Next, Windows will detect a USB Serial device and will install a second driver. On Windows XP systems,
there can be a delay of up to 10 seconds between the installation of both drivers, which sometimes leads
to the wrong conclusion that the installation is complete after the first driver is installed. On Windows
Vista and Windows 2000 systems, there is only very little delay.

When the installation is complete, a new virtual COM port will be created.

If necessary, the number of this COM port can be changed in the Windows Device Manager. Click on the
‘+’ sign next to the entry marked as “Ports (COM & LPT)”. This will expand the entry to list all available
COM ports on your computer. The port for the multiplexer is listed as “MiniPlex Serial Port (COMx)” where
“COMx” is the name of the newly created serial port.

To change this port number, double click on the “MiniPlex-3 Serial Port (COMx)” entry to open the
property page for this port. Next, select the “Port Settings” tab and click on the “Advanced…” button. In
the appearing window the assigned port number can be changed. Do not change any other setting in this
window.

It is possible to select a port number that is already present on the computer, like COM1. The original
COM1 port will then be disabled as long as the multiplexer is connected to the computer. This feature
allows the port number to be set in a low range from COM1 to COM4, to accommodate software that only
allows COM1 to COM4 to be selected.

More than one multiplexer can be connected at the same time. Every new unit will create a new virtual
COM port. Once created, the COM port will always be assigned to the same multiplexer regardless of the
USB port being used.

Windows allows a maximum of 256 COM ports. However not all software may be able to select COM ports
numbered above COM9.

When installing updated drivers, uninstall the original drivers first with the “Add/Remove Programs” icon
in the Control Panel or use the “Update Driver” button on the Driver page of the “MiniPlex Serial Port”
property-page.

Mac OS X

The OS X driver is available as a disk image file (.dmg) and can be found on the supplied CD in the “USB
Driver” folder. Run the installer by double clicking on the icon. Follow the instructions on the screen.
When the installation is complete, plug in the USB cable of the MiniPlex. The MiniPlex will show up in the
ports list of your navigation software as MiniPlex-xxxxxxxx where the xx’s represent the serial number of
the MiniPlex.

14

Network Interface

(MiniPlex-3E, MiniPlex-3E-N2K)

A network interface connects the multiplexer directly to a network with possibly more than one device.
There can be more than one multiplexer connected to a network and/or more than one device that needs
to communicate with a multiplexer.

Network Basics

In order to understand how a networked multiplexer works and how to connect to it, it is necessary to
know a little bit about IP addresses, port numbers and protocols.

IP Address

Every device on a network needs a unique number to be able to identify that device. This allows us to
send a message to one single device on a network. These unique numbers are called MAC addresses and
every device in the world that is connected to a network has a unique MAC address. The MAC address of
a MiniPlex-3E or -2Wi multiplexer is printed on the serial number label and looks like

00-20-4A-E4-28-58

These addresses are a bit cryptic and not easy to work with. Therefore a mechanism is used to assign a
more easy to read number to a device, called an IP address. An IP address consists of four numbers
grouped together, separated by dots. Each number can range from 0 to 255. An IP address looks like
this:

192.168.1.45

Assigning an IP address to a device could be compared to sticking a coloured label to your house. Now
the postman only needs to remember the colour of your label instead of your complete address. Of
course, someone needs to manage a list that matches the colour to your address in order to prevent two
houses of receiving the same coloured label. Networks and network devices have mechanisms built in
that take care of this so we don’t have to worry about it (it’s called ARP or Address Resolution Protocol).

Netmask

Another tricky bit of networking is a netmask. A netmask basically determines which part of an IP
address is the network address and which part is the device address. In its most basic form, a netmask
consists of four numbers, similar to an IP address, that are either 255 or 0. And the 255’s always come
first. A device always has an IP address AND a netmask, for instance:

192.168.1.45 and 255.255.255.0

This combination of IP address and netmask tells us that the first three numbers of the IP address are
the network address (192.168.1) and the fourth (45) is the device’s address. It also means that this
particular combination limits the number of devices on this network to 254 (0 and 255 are reserved).

A network address allows us to send a single message to all devices on the network, instead of sending it
to one single device. This is called a broadcast (see below). In this example, the broadcast address is

192.168.1.255. The last number here is 255, which means that it targets all devices on the network.

If we have an IP/netmask combination of 192.168.1.45/255.255.0.0, it means the network address is

192.168 and the device’s address 1.45, that there are 65534 possible devices (0.0 and 255.254 are
reserved) and that the broadcast address is 192.168.255.255.

If you’re completely lost at this point, don’t worry. Just remember two things:

• All devices on a single network must have the same netmask

• All devices on a single network must have the same network address

So when the netmask for example is 255.255.255.0, the first three numbers of the IP addresses must be
the same.

Port Number

A port number can be seen as a sub address within one single device. When a message is sent over the
network, it always contains the IP address of the sender, the IP address of the receiver and a port
number. This port number is just a logical number that determines the type of data in the message.

Web servers for instance, always listen to messages that have port number 80. If you start your web
browser and enter the name of a web site, the request to show the contents of a page is sent to a web
server using port number 80. Similarly, your mail program always uses port number 110 to retrieve mail
from a mail server and port number 25 to send mail to a mail server.

15

The use of different port numbers allows us to use the same physical device on a network for different
services.

Port numbers are not chosen arbitrarily, they are standardized and controlled by an organization called
IANA.

Our multiplexers all use port number 10110, which is a registered port for NMEA data.

Protocols

Two transport protocols are available for sending data over the network: UDP and TCP. UDP can be used
in two different modes: Broadcast and Directed.

UDP Broadcast

NMEA sentences are broadcast on the network using UDP messages. Every device on the network will
receive these messages. At the same time, any device on the network can send data to the multiplexer,
either to its IP address (directed) or as a broadcast. UDP Broadcast has the following properties:

• Every device on the network will receive NMEA data from the multiplexer.

• Every device on the network can send NMEA data to the multiplexer.

• Other MiniPlex-3E/2Wi’s on the same network will also receive each other’s data. It is therefore

possible to send NMEA data over the network from NMEA device to another. Care should be taken to
prevent buffer overflows by selectively routing the desired NMEA data to an NMEA output at the
receiving end and blocking unwanted NMEA data.

• Routers do not pass UDP Broadcasts from one network to another so this mode can only be used on
one network.

• Delivery of NMEA data is not guaranteed, messages can be lost.

• Wi-Fi routers often assign a low priority to UDP broadcasts, resulting in dropped messages. Typically

up to 5% of the messages gets lost.

UDP Directed

With directed UDP data is sent to a specific IP address. The advantage is that it travels across routers and
networks and can therefore also be used to send NMEA data over the Internet. Any device on the
network can send data to the multiplexer either to its IP address (directed) or as a broadcast. Directed
UDP has the following properties:

• Travels across routers/networks and the Internet.

• Higher change of delivery than UDP broadcast.

• Every computer on the network can send NMEA data to the multiplexer.

• Only one computer can receive NMEA data from the multiplexer.

• Delivery of NMEA data is not guaranteed, messages can be lost.

TCP

When using TCP, a device sets up an exclusive connection with the MiniPlex. The TCP protocol is reliable,
which means that when data gets lost on the way from one device to another, it is automatically
retransmitted. Both the MiniPlex-3E and the MiniPlex-3Wi are limited to one TCP connection at a time.

TCP has the following properties:

• Travels across routers/networks and the Internet.

• Only one computer or other device may communicate with the multiplexer.

• Reliable connection. Lost messages are automatically retransmitted.

Although TCP might seem the best option from the above, it is favourable to use UDP. Compared with
TCP, UDP will minimize network bandwidth. To send periodically updated sensor data, it is usually more
appropriate to NOT use a guaranteed-delivery protocol like TCP. In navigation applications, the best thing
to do in the rare event that a message doesn't get through is to simply wait for the next message. The
TCP protocol forces retries which increase network traffic unnecessarily.

UDP resembles NMEA the most because NMEA is also a message based broadcast protocol without any
acknowledgements or retries.

Assigning IP addresses

When devices are connected to a network, they all must have a unique IP address and a matching
netmask. One way of achieving this is to set the IP address and netmask of each device manually. The
other way is to let a DHCP server take care of this.

DHCP is an acronym for Dynamic Host Configuration Protocol and it is a mechanism to automatically
assign IP addresses to devices (hosts) on a network. A DHCP server on a network will respond to
requests from DHCP clients to obtain an IP address.

16

In a typical network environment, a router acts as a DHCP server while other devices such as computers,
laptops, tablets and smartphones are DHCP clients, receiving IP addresses from the DHCP server. This
ensures that you can connect these devices to the network without worrying about IP addresses,
netmasks and gateways - al of this is taken care of by the DHCP server.

The MiniPlex-3Wi acts as a WiFi access point with a DHCP server built-in. When a device joins its WiFi
network, it will automatically receive an IP/netmask from the MiniPlex-3Wi. The only thing you have to do
is to enter the fixed IP address of the MiniPlex-3Wi (10.0.0.1) in your navigation software.

The MiniPlex-3E is completely different in this respect. It has a DHCP client and thus relies on a DHCP
server already present on the network to obtain an IP/netmask automatically. If no DHCP server is
present, you have to manually assign an IP/netmask. This is the case for instance, if your “network” is
just the MiniPlex-3E and a computer. Obviously you will need to assign a manual IP address and netmask
to your computer too in this case.

Auto-IP

When DHCP request remains unanswered, a device assigns itself an IP address in the range of

169.254.0.0 to 169.254.255.254 with netmask 255.255.0.0. This is called an Auto-IP address. Although
two devices with an Auto-IP address on the same network can perfectly communicate with each other,
this is not a desired situation because these addresses are assigned totally at random. So every time a
devices powers up, the address changes within the Auto-IP range and you’ll never be sure of its IP
address. Also, the time it takes for a device to auto-assign varies wildly from a few seconds to over a
minute.

MiniPlex-3E Network Setup

When you are going to use a MiniPlex-3E, it is important to know whether your network has a DHCP
server. If a DHCP server is present on the network, you don’t need to manually assign a fixed IP address
to the MiniPlex-3E if the following conditions are met:

• The DHCP server always assigns the same IP address to the same MAC address

• The DHCP pool of free addresses will never be exhausted

This ensures that the MiniPlex-3E will always get the same IP address. The best practice however is to
assign a fixed IP and netmask to the MiniPlex-3E.

In order to find the MiniPlex-3E on the network, first select TCP with the Port selector in the “MiniPlex
Connection” box. After this, the Tools menu will show a “MiniPlex-3E” sub-menu. From this sub-menu,
select “Search…”

This will bring up a window showing the MiniPlex-3E’s
found on the network (Figure 15). In this case there’s
only one and its IP address appears to be 192.168.1.95.
The cryptic number in brackets is the MAC address of the
multiplexer, which is also printed on the serial number
label. If you select this entry and click OK (or double-click
on the entry), the window closes and the IP address is
transferred to the Host field in the “MiniPlex Connection”
box. At this point you can click on the Connect button to
open a connection with the multiplexer and the MPX­Config-3 window should show some NMEA sentences in
the NMEA viewer.

If the listed address is an Auto-IP address in the

169.254.x.x range, click on the “Change IP Address”
button to assign a sensible IP address to the MiniPlex.
When done, the window will show the MiniPlex with the
newly assigned address and it can be selected for normal
use. You can use the “Factory Reset” button to restore
the network settings to its factory defaults if necessary
(DHCP and UDP broadcast).

If you’re happy with the DHCP assigned IP address and the default TCP mode, there is no further network
configuration required and you can proceed with the normal multiplexer configuration as outlined in
chapter “MPX-Config” on page 27.

To change any of the network settings, make sure the IP address of the multiplexer is in the Host field in
the “MiniPlex Connection” box and select menu Tools ! MiniPlex-3E ! Network Setup… This will open the
“MiniPlex Network Settings” as shown in Figure 16.

Figure 15

17

These are the factory default settings.
The IP address shown here is 0.0.0.0,
which means the multiplexer is set to
DHCP. This address is different from
what you have entered in the Host
address field on the main window
because that is the address that the
MiniPlex received from the DHCP
server.

You can now enter the desired IP
address and a netmask that matches
your network. The Gateway IP can be
left to 0.0.0.0 if you are not going to
set the multiplexer to UDP Directed.

The example in Figure 17 shows fixed
IP settings.

If you set the multiplexer to UDP
Directed, you must enter a destination
IP address in the Destination field. If
this IP address is not on the same
network as the multiplexer, you must
also enter the address of your network
gateway in the Gateway IP field.

Please note that when UDP Directed is
enabled, you will not receive any NMEA

data from the multiplexer anymore
when the IP address of your computer
is different from the Destination IP. The network settings however can always be changed regardless of
this setting.

If you click on the OK button to activate the settings, a progress bar will appear because the network
interface must be restarted and this takes approx. 7 seconds. The new IP address and protocol will
appear automatically in the Host and Port controls on the main window of MPX-Config-3 when the
process is completed.

If you need to change the network settings back to DHCP, set the IP Address field to 0.0.0.0 and click
OK.

In some cases, the settings of the multiplexer cannot be verified after change, for instance because the
IP address is changed from a fixed address to DHCP (0.0.0.0) or when an IP address is entered which is
not on your network. In this case, a warning will appear.

Search

The search function (menu Tools ! MiniPlex-3E ! Search…) will almost always find any MiniPlex-3E on
the network, even if it has been configured with the wrong IP/Netmask combination for the network it is
connected to. In rare cases MiniPlex-3E cannot be found.
See the paragraph “Network Recovery” below how to deal
with this situation.

The search result window (Figure 18) has two buttons
that allow you to restore the network settings to the
factory default values and to change the current IP
address in case it is outside your network. In that case
the normal network setup cannot be used.

Figure 16

Figure 17

Figure 18

18

Network Recovery

In rare cases a MiniPlex-3E might not show up in the search
results window due to a possible misconfiguration in the Network
Settings. This might happen when duplicate IP addresses exist on
the network or the multiplexer has an illegal IP address. To
recover from such a situation, a new IP address can be assigned
with menu option “Tools ! MiniPlex-3E ! Assign IP”.

In the “Assign IP Address” dialog (Figure 19), enter the MAC
address of the multiplexer. This MAC address can be found on the
label on the topside of the multiplexer, below the serial number.

Enter the MAC address with the fields separated by dashes as
shown. Then enter a valid IP address and click on OK. A progress
bar will appear during the update process, which will take approximately 10 seconds. After that, the
multiplexer can be reached again through the normal “Network Settings” dialog.

Figure 19

19

NMEA 0183 Ports

The NMEA 0183 ports are the inputs/listener ports and outputs/talker ports on the MiniPlex-3, which
connect to NMEA 0183 ports on navigation instruments, chart plotters etc. There are many
interpretations and variations of NMEA 0183 ports so we’ll explain a few things first.

NMEA 0183 Signals

Although the NMEA 0183 standard specifies the signal names, voltage levels and connection methods
very clearly, the reality is far from this ideal world.

The most important property of an NMEA 0183 port is that the connections or wires are labelled A and B
and that it uses a differential signalling scheme. This means that data is transmitted on both wires, but in
“opposite direction”. Both wires are driven between 5V and 0V and opposite of each other: when wire A is
at 5V, wire B is at 0V and when wire A is at 0V, wire B is at 5V. The advantage of this signalling scheme
is that it is very insensitive to electrical interference.

NMEA A and B are often labelled as NMEA + and - respectively. When connecting devices, simply connect
NMEA A to NMEA A or NMEA + and NMEA B to NMEA B or NMEA -.

Some devices even have NMEA + and NMEA – the other way around. It is perfectly safe to swap the
wires if no signal is received when connected to an NMEA 0183 port of the MiniPlex-3.

Things get complicated when manufacturers don’t follow the NMEA 0183 standard, which is very often
the case. Many devices have an NMEA 0183 interface, which is electrically speaking an RS-232 interface.
The only resemblance with the NMEA 0183 standard is the format of the data transmitted. Electrically,
they are an entirely different world. The used signal names differ wildly and often lead to confusion.
When a device has a NMEA input with connections “Data In” and “Data Return” it is often not clear
whether this input is galvanically isolated or if “Data Return” is simply another name for “Signal ground”.

Instead of being fully compatible with the NMEA 0183 standard, many devices use a single-ended
signalling scheme where data is transmitted on one a single wire while the power ground provides the
return path. Single ended devices often have connection names like TX and Gnd (transmit and ground)
on the NMEA output and RX and Gnd (receive and ground) on the NMEA input. Also used are Data Out,
Data In and Signal Ground. Mix these with standard NMEA connections and confusion is imminent!

The MiniPlex-3 Series multiplexers takes away the confusion by offering galvanically isolated NMEA inputs
and outputs. Because of this isolation, a ground reference no longer exists: both the A and B signals of
an NMEA port are completely “floating”. This means that you don’t have to think about the nature of an
input or output of the device you want to connect to multiplexer. Any NMEA output of a device can be
connected to an NMEA input of the multiplexer while an NMEA output of the multiplexer can be connected
to any type of input of your device or instrument.

NMEA 0183 Inputs

The MiniPlex-3 has four NMEA inputs called In1 to In4. Each input should be connected to one output
only. These inputs are galvanically isolated from the multiplexer, as specified by the NMEA 0183
standard.

The default communication speed of the NMEA 0183 inputs is 4800 Baud (NMEA standard) and it can be
set to any value from 4800 to 57600 Baud using MPX-Config-3. Set the speed of an input to 38400 Baud
if it will be connected to an AIS receiver or transponder.

Connect the A and B terminals of the NMEA input on the multiplexer to the A and B terminals of the
NMEA 0183 output on the navigation device as shown in Figure 20 on the left. These terminals may also
be labelled as Data+/Data-, TX+/TX-, Out+/Out– or ve+/ve-.

Some navigation devices have single ended outputs with only one data terminal. Connect this terminal to
the A terminal of the multiplexer input, and connect the ground of the navigation device to the B terminal
of the multiplexer input as shown on the right in Figure 20. The navigation device’s data ground is often
combined with its power supply ground. In that case, connect the power ground of the navigation device
to the B terminal of the multiplexer input.

20

Figure 20

NMEA 0183 Outputs

The MiniPlex has two NMEA 0183 outputs called Out1 and Out2. Each output is capable of driving up to
four NMEA 0183 inputs.

The default communication speed of NMEA Out1 is set to 4800 Baud while NMEA Out2 is set to 38400
Baud. This speed can be set to any value from 4800 to 115200 Baud using MPX-Config-3.

Connect the A and B terminals of the NMEA output on the multiplexer to the A and B terminals of the
input(s) on the instrument(s). These terminals may also be labelled as Data+/Data-, RX+/RX-, In+/In–
or ve+/ve-.

Some instruments may have single ended inputs, with only one data terminal. Connect this terminal to
the A terminal of the multiplexer output, and connect the B terminal of the multiplexer output to the
ground terminal of the instrument. Figure 21 shows several examples of differential and single ended
connections and combinations of both.

Figure 21

The shield terminals on the multiplexer (Shld) can be connected to the shield of the cable if available.
This should always be done on one end of the cable only, preferably on the end that is connected to an
NMEA output.

Multiplexer

In A

In B

Instrument

Out A/+

Out B/-

Differential

Multiplexer

In A

In B

Instrument

TX/Out

Ground

Single ended

Multiple differential and

single ended listeners

Instrument

In A/+

In B/-

Multiplexer

Out A

Out B

Differential

Instrument

RX/In

Ground

Single ended

Multiplexer

Out A

Out B

Instrument

In A/+

In B/-

Multiplexer

Out A

Out B

Instrument

In A/+

In B/-

Instrument

RX/In

Ground

21

Combining Ports

It is sometimes necessary to combine an input and an
output of the multiplexer to connect to an instrument. One
of the most common cases is the connection between a
GPS and the multiplexer. While some GPS receivers have
properly designed NMEA ports, many only have an RS-232
port which is single ended with three terminals: TxD (data
out), RxD (data in) and Ground. Figure 22 shows how to
connect such a GPS to the multiplexer.

SeaTalk

SeaTalk® is a proprietary protocol developed by Raymarine®. This protocol is used for communication
between Raymarine navigation instruments like the ST40, ST50 and ST60 series.

To be able to use these instruments with commonly
available navigation programs or to feed their data into
other non-Raymarine instruments, the SeaTalk data
needs to be translated into NMEA. Even Raymarine’s own
navigation software, Raytech Navigator, needs this
translation.

The MiniPlex-3 can be directly connected to a SeaTalk
network. It will translate all SeaTalk data required for
navigation into NMEA sentences. Input In1 can be set to
SeaTalk mode (“SeaTalk -> NMEA”) and should be
connected as shown in Figure 23.

Figure 24 shows how to power the MiniPlex-3 from the
SeaTalk network. The SeaTalk cable is connected to
In1/SeaTalk and at the same time the red wire and
shield are connected to the power terminals of the
multiplexer.

Figure 22: Connecting a GPS with a serial port

to the multiplexer.

Figure 24: Power and data from the SeaTalk

network.

GPS

TxD/Out

Ground

RxD/In

Multiplexer

In A

In B

Out A

Out B

SeaTalk cable

Multiplexer

In 1A

In 1B

Red

Yellow

D

In1/SeaTalk

SeaTalk cable

Multiplexer

Red

Yellow

+12V

Gnd

In 1A

In 1B

D

In1/SeaTalk

Figure 23

22

NMEA 2000

MiniPlex-3 multiplexers with an NMEA 2000 port (the “-N2K” models) are capable of communicating on
an NMEA 2000 network. NMEA 2000 messages, frequently called PGN’s, are translated into NMEA 0183
sentences. The MiniPlex-3 will also translate NMEA 0183 sentences and SeaTalk data into NMEA 2000
PGN’s.

Since the conversion between NMEA 2000 and NMEA 0183 works in both ways and for all NMEA 0183
inputs and outputs on the MiniPlex-3 including the Host ports, it will integrate NMEA 2000 and
NMEA 0183 almost seamlessly. NMEA 0183 data from “older” devices will be available on new NMEA 2000
capable chartplotters and autopilots. Similarly, every navigation software outputting NMEA 0183
sentences will be able to send waypoints to chartplotters and drive autopilots on the NMEA 2000 network.

SeaTalk1 data received by the multiplexer is also available on the NMEA 2000 network. Transmission of
SeaTalk1 data from NMEA 0183 and NMEA 2000 will be available soon as a firmware update.

The MiniPlex-3 can be seen as a central navigation server/database, making received navigation data
available on all three interface/bus/network types.

Figure 25

On an NMEA 2000 network, data is exchanged using defined messages often called PGN’s. The PGN is
actually the number (Parameter Group Number) of the message, which specifies which message it is and
which data (parameters) it contains. For instance, PGN129029 contains the GPS position and PGN129026
contains the COG and SOG. There are a lot of different PGN numbers defined which are pretty hard to
remember, so we chose to keep working the same concept as with NMEA 0183: sentence addresses with
known acronyms like RMC for GPS position.

Therefore the Sentence Filter & Routing feature of the multiplexer still works with well-known NMEA 0183
sentence addresses. NMEA 2000 PGN’s are first converted into NMEA 0183 sentences and then filtering
and routing is applied.

PGN’s for which no NMEA 0183 equivalent exists, are ignored by the multiplexer. It is however possible to
enable an option (see Figure 41) to convert those PGN’s into an $MXPGN sentence. This allows software
to read and decode NMEA 2000 PGN’s without special hardware. Such PGN’s could contain battery or
alternator status, engine data or an electrical switch position. Converting these PGN’s to an $MXPGN
sentence allows developers to easily read NMEA 2000 data with existing NMEA 0183 sentence parsers.
Such a sentence looks like this:

$MXPGN,01F112,2807,FC7FFF7FFF168012*11

The multiplexer can also be set to convert every single PGN into an $MXPGN sentence, allowing software
to have full control over the NMEA 2000 network. The same $MXPGN sentence can also be used to send
data to the NMEA 2000 network. If the multiplexer receives a correctly formatted $MXPGN sentence, it
will be converted to an NMEA 2000 message and sent onto the NMEA 2000 network.

The Technical Reference in the back of this manual contains a detailed description of the $MXPGN
sentence and how to use it.

Navigation

Server

SeaTalk1

NMEA 0183

NMEA 2000

23

Connecting to the NMEA 2000 network

The MiniPlex-3 is equipped with a standard Micro-C style male connector. Connect the multiplexer with a
spur cable and a T-piece to the NMEA 2000 backbone.

NMEA 2000 networks must always consist of a powered backbone with terminators, to which the
multiplexer and other devices must be connected. It is not possible to simply connect two NMEA 2000
devices directly together. An NMEA 2000 backbone needs to be powered and terminated on both ends.

24

Power Supply

The multiplexer must be powered from an externally supplied DC voltage from 8 to 35V. The power
supply connection is protected against reversed polarity.

Indicators

The LEDs on the MiniPlex provide information about the status and operation of the multiplexer. When
the multiplexer is power up, all LEDs flash once.

Green (NMEA 2000): This LED flashes when an NMEA 2000 PGN is received.

Green (NMEA 0183): This LED flashes upon reception of a valid NMEA sentence. During a firmware

update, this LED flashes upon reception of a firmware block.

Red (Overflow): This LED flashes on a buffer overflow, indicating that a currently received NMEA

sentence will be lost.
During start-up, this LED is on for a short moment while the multiplexer checks if
firmware is loaded or if a firmware update is initiated by MPX-Config-3. If firmware
is found, the LED goes off. When the LED stays lit, no firmware was found.
During a firmware update, this LED is on. When the update is completed, the LED
goes off. If the LED stays on after a firmware update error, it indicates that no valid
firmware is present.

25

Data Throughput

A multiplexer is not the Holy Grail for connecting NMEA 0183 devices. It should be fairly obvious that if a
device combines data from four sources, the total amount of data that must be forwarded is the sum of
the amount of each source. Still, the NMEA 0183 standard specifically limits the communication speed to
4800 Baud or bits per second, which equals 480 characters per second.

So, when using a multiplexer, a situation could arise where more data is received than can be
transmitted because of the speed limitations of the NMEA 0183 outputs. Such a situation will lead to an
overflow of the input queues of the multiplexer.

When an NMEA 0183 sentence is being received and a queue is filled up, this sentence is discarded
because the MiniPlex only forwards complete NMEA 0183 sentences. This event is indicated by a blink of
the red LED. The indicators in the “Input Overflow” section of MPX-Config-3 will also show this event.

In its default factory setting, as shown in Figure 26, the data flow through the MiniPlex is very
straightforward: the data received on the NMEA 0183 inputs and from the NMEA 2000 network is always
sent to the host interface(s).

Figure 26

In addition to this, the same data is also sent to Out2, as indicated by the checkboxes in the section
“Input Settings”. The section “Output Settings” shows that data from the computer (Host Data) is sent to
Out1 only. Host data is also sent to the NMEA 2000 network.

This basic configuration allows you to combine data from navigation instruments and send it to a
computer using the host port and to a chart plotter connected to Out2, while at the same time the
computer can control an autopilot connected to Out1.

The default speed setting of the inputs and outputs ensures that there will be no queue overflows.

Please note that the default communication speed of Out2 is 38400 baud. Most chart plotters support this
high speed for reception of AIS data. However, if you want to connect this output to a repeater display or
a VHF radio, the speed of Out2 must be lowered to 4800 baud. If this leads to excessive overflows, it is
necessary to reduce the amount of data sent to this output. This can be achieved by changing the default
routing settings (disable certain inputs for Out2) or by using the “Sentence Filtering & Routing” feature of
the MiniPlex.

Now back to data throughput. The standard speed of an NMEA 0183 port is 4800 Baud or bits/second,
representing 480 characters per second. It is quite obvious that when four inputs receive data at 480
char/s and all of this data must be sent out again on an output with the same bandwidth of 480 char/s, a
huge problem will arise. In the default configuration of Figure 26, this problem does not occur because
the speed of Out2 is set to 38400 Baud (3840 char/s). When Out2 is not used, set it to the highest speed
or disable routing of any of the inputs to Out2. When Out2 is connected to a chart plotter, try to choose
the highest speed the plotter is capable of.

If data from more than one input needs to be routed to an output operating at 4800 Baud, problems with
data throughput can arise when too much data is sent to this output.

NMEA 0183 data tends to be sent in bursts. Some devices like depth sounders or wind instruments only
send one sentence per second. A GPS however may send bursts of up to 13 sentences every two
seconds. While the average throughput over time may be low, an input might fill its queue quite rapidly

26

when a burst of sentences is received. The queues in the MiniPlex are quite large and can contain up to
30 sentences of GPS data.

A couple of occasional blinks of the red LED over a period of a few seconds means that large bursts of
sentences are received and a queue is hitting its limit. Some sentences are discarded but most of them
will be forwarded without problems. Such a situation is totally acceptable and would mean that for
instance one depth, wind or position update is missed every few seconds.

A quite different situation may arise with some fluxgates or gyrocompasses. These devices may send
their heading sentences with a speed up to 40 sentences per second! Instead of queuing a burst of
sentences every one or two seconds, the multiplexer must queue a constant stream of sentences,
possibly utilizing the maximum bandwidth of the multiplexer. Such a situation can lead to a queue that is
constantly filled up to its maximum capacity. If this happens, use the sentence filter to reduce the
frequency of the heading sentences and/or block all sentences which do not need to be sent to the output
which is the bottleneck.

When the red LED blinks severely or stays lit almost continuously, it is
strongly recommended to investigate which instrument or input leads to
this overflow. The MPX-Config-3 utility will show on which input the
overflow occurs by a blinking indicator in the “Input Overflow” section.
Opening the Statistics window (Figure 27) from the Tools menu will give
an insight about the amount of data in each queue and whether it is filled
constantly or occasionally.

Some general rules apply for reducing overflow situations. A simple rule
of thumb is that an overflow can never occur if the speed of an output is
equal to or higher than the combined speeds of all inputs that are routed
to that output. For example: if the multiplexer is in its default
configuration and all four inputs are set to 4800 Baud, the minimum
output speed equals 4 x 4800 = 19200 Baud. This rule is only a hard rule
when the input bandwidth is fully utilized i.e. an instrument is sending
data continuously. This is hardly ever the case. As mentioned earlier,
NMEA 0183 data is often sent in bursts, resulting in a much lower overall
bandwidth. It could be perfectly feasible to have a system with four
instruments connected to the multiplexer, while running all in- and
outputs on 4800 Baud without a single overflow.

There are several ways to resolve overflow situations:

1. Configure the instruments on the listener ports to send less data or with greater intervals. GPS
receivers can sometimes be configured for this.

2. Use the sentence filter of the multiplexer to block unwanted sentences. Unwanted sentences are
discarded immediately and do not occupy queue space or bandwidth.

3. For sentences that should not be blocked, setting a divisor in the sentence filter may lower their
rate. A gyro may be throttled down to 10 sentences per second or even less. From the GPS
output, the rate of the sentences containing satellite information could be lowered to once every
10 seconds instead of being output every time a position is output by the GPS.

4. Use the routing options to select which input is routed to an output or use the routing options in
the sentence filter to selectively route NMEA 0183 sentences to an output.

5. Increase the speed of the NMEA 0183 output that causes the bottleneck. This will only work when
the connected equipment also supports higher communication speeds. Connected ports must
always match their communication speed (Baud rate).

Figure 27

27

MPX-Config-3

The MiniPlex-3 multiplexer can be configured with a configuration tool called MPX-Config-3. This tool can
be found on the accompanying CD. There is no installer for this tool, just start it from the CD or copy it to
a suitable folder on the hard disk of your computer and start it from there.

The multiplexer itself is configured with proprietary NMEA 0183 sentences. MPX-Config-3 sends these
sentences to the multiplexer immediately when you change a setting. Settings do not have to be stored
explicitly except for the Sentence Filter & Routing.

All configuration settings are stored in the multiplexer’s non-volatile memory. These settings are retained
without power supply.

Figure 28: MPX-Config-3 main window

The window of MPX-Config-3 is divided into four sections from top to bottom: the menu, the NMEA
viewer, the controls and the status bar. The menu basically controls the MPX-Config-3 program. The
NMEA viewer shows the NMEA 0183 sentences received from the multiplexer. These sentences include
the NMEA data received by the multiplexer on its inputs as well as status messages generated by the
multiplexer (sentences starting with $PSMD). The controls determine the operation and configuration of
the multiplexer. The status bar shows the name or type of multiplexer that is connected, its internal
software (firmware) version number and its serial number. This information is useful when you need
technical support. Also shown are the optionally loaded or saved configuration file and a line counter
when you have started a log file.

28

Menu

The menu contains two sub-menus: File and Tools. Some options of these menus are disabled or not
visible, depending on the type of connected multiplexer or on the status of the connection.

The File menu offers the following choices:

Log NMEA… Start writing NMEA data to a log file. A log file is a plain text file and can

later be opened by any text editor to examine the data. The Log counter on
the status bar will show the number of NMEA sentences that are currently
written to the log file.

Log Diagnostic Info… Start writing to a log file with the addition of a time stamp at the beginning

of each NMEA sentence.

Stop Log Stop writing NMEA data to the current log file and close that file.

Load Configuration… Load a previously saved configuration file into the multiplexer. The current

configuration will be overwritten. A configuration file stores all settings
made with MPX-Config-3.

Save Configuration Save the current configuration to a previously file.

Save Configuration As… Save the current configuration to a new file.

Update MiniPlex Firmware… Load new a firmware file into the multiplexer.

Exit This exits MPX-Config-3.

The Tools menu offers the following choices:

Show Statistics Opens a window showing bars that indicate how much NMEA data is stored

in the input queues. This is a useful option for diagnosing data congestion
and overflow situations as mentioned in paragraph “Data Throughput”. A
queue that is filled constantly can lead to unacceptable delays in data
transfer.

MiniPlex-3E Opens a sub-menu for the MiniPlex-3E.

Reset Factory Settings… Reset the multiplexer to its default factory configuration.

About Show a window with version information.

The MiniPlex-3E sub-menu offers the following choices:

Network Setup… Open a window to setup the network parameters of a MiniPlex-3E.

Search… Search the network for MiniPlex-3E’s. A window is shown with the search

results.

Assign IP… Assign an IP address to a MiniPlex-3E using its MAC address.

29

Controls

MiniPlex Connection

Before being able to configure the multiplexer, a connection must be set up. Use the Port selector either
to select the COM port of the multiplexer or to select TCP or UDP when using a network connection.

COM Port

When using a multiplexer with a USB port, select the COM port
that was assigned after installing the driver. Click on the Connect
button to initiate the connection. MPX-Config-3 will immediately
read the current configuration from the multiplexer.

Network

When a network connection is used to connect to a MiniPlex-3E, select TCP or UDP as shown in Figure 30.
Use the protocol as set in the “MiniPlex-3E Network Setup” on
page 16.

When TCP or UDP is selected, a Host field appears where you must
enter the IP address of the multiplexer. Enter the IP address as
specified in the “Network Setup”. Click on the Connect button to

initiate the connection. MPX-Config-3 will immediately read the
current configuration from the multiplexer.

If the IP address is unknown, you can use menu Tools ! MiniPlex-3E ! Search… to detect the MiniPlex-
3E on your network. Select the MiniPlex-3E from the list and click the OK button. Its IP address will be
transferred automatically to the Host field on the main window of MPX-Config-3.

UDP All

The Port selector also offers a UDP All option, which can be useful when more than one MiniPlex-3E’s are
connected to the same network, which are all set to UDP. These multiplexers will all send (broadcast)
NMEA 0183 data on the network and any application listening to port 10110 will receive this data from all
multiplexer. MPX-Config-3 will only listen to data from the IP address entered in the Host field when set
to UDP. However when UDP All is selected, MPX-Config-3 will display NMEA data from ALL multiplexers on
the network sending data using UDP. When connecting, MPX-Config-3 will therefore not read the
configuration because all multiplexers would respond and return their configuration. Only the version
sentence PSMDVER is requested and displayed in the NMEA viewer.

The effect of changing a setting in this mode depends on the IP address entered in the Host field. If it
contains an IP address of a multiplexer, the configuration setting is sent to that multiplexer only. If the
Host field contains a broadcast address however, the configuration setting will be sent to ALL
multiplexers. A broadcast address is an address with 255 in the device part of the IP address. In case of
the address used above, 192.168.1.50, the broadcast address for that network would be 192.168.1.255.

In short: do not use this option when a single MiniPlex-3E is used.

Reading the configuration

When the Connect button is clicked, MPX-Config-3 opens a connection to the multiplexer and
automatically retrieves its current configuration. The tabbed configuration pages will be enabled upon
success and the LED on the Connect button will become green. Depending on the type of connected
multiplexer, the NMEA 2000 page may or may not be visible, as well as any other NMEA 2000 related
settings.

If a “Multiplexer does not respond” message appears, you may have selected the wrong COM port. An
“Unable to connect” or “Socket error” message indicates a wrong IP address or protocol (TCP or UDP).

If you exit MPX-Config-3, the connection settings will be saved and reloaded with the next start of MPX­Config-3. When you select a different port while being connected, MPX-Config-3 disconnects from the
multiplexer.

You can also instruct MPX-Config-3 to retrieve the configuration from the multiplexer with the “Read
Configuration” button (Figure 31).

Figure 29

Figure 30

30

Manual NMEA input

MPX-Config-3 allows manual entry of NMEA sentences for testing,
configuration etc.

Type the desired NMEA sentence in the edit box and click on the
Send button or press the enter key. MPX-Config-3 will keep a
history of entered sentences/commands. These can be selected by
clicking on the small arrow on the right side of the input field. A
selected sentence can be sent again by clicking on the Send
button or pressing the Enter key. It can also be edited prior to
sending.

Preceding the NMEA sentence with a $ is optional, MPX-Config-3
will add it if omitted. The input is case sensitive, so whatever you
type will be sent to the multiplexer literally. Since all NMEA
sentence are uppercase, you have to enter them as uppercase.

Any sentence starting with $PSMD will be recognized by the
multiplexer as a configuration command and will be processed as

such. Any other sentence will be sent to the NMEA outputs.

This feature can also be used to test if an NMEA input or output is
functional: Connect an NMEA output to an input, make sure the default route from that input to that
output is enabled and type an arbitrary text of at least 6 characters in the “Manual NMEA Sentence Input”
field. This text should appear in the NMEA viewer when you click on the Send button or press the enter
key.

Viewer Options

The NMEA Viewer area (Figure 32) offers a few controls that make observing NMEA data
easier.

Clear

This button clears the NMEA Viewer window.

No Scroll

When this option is enabled, a list of incoming NMEA sentences will be displayed that will
be refreshed constantly when new similar sentences are received. This feature allows you
to closely examine the types of sentences that are received from the connected
instruments. Any proprietary NMEA sentences that are generated by the multiplexer are
also listed. These sentences start with $PSMD.

Tag Blocks

This option will show any TAG blocks that precede a sentence. TAG blocks can be seen

when they are enabled (see “Channel Information”), when the input selector is set to a
specific input or when the Capture function of the sentence filter is activated. Of course,
when a device that is connected to the inputs of the multiplexer sends TAG blocks, they will also be
visible.

Input selector

The input selector allows you to selectively see sentences from one specific NMEA input of the
multiplexer, the NMEA 2000 interface or from the conversion results. Setting this selector to any setting
besides “All Inputs” will enable TAG blocks automatically. These are used to identify the input a sentence
is received on. When set to “All Inputs”, the original TAG block setting is restored.

Overflow

The overflow indicators show which input suffers from a queue overflow (inputs 1 to 4 from left to right).
See the section “Data Throughput” on page 25 for ways to prevent overflow situations with different
instruments.

Figure 31

Figure 32

31

NMEA Inputs/Outputs

This page allows you to set the communication speeds of the NMEA inputs and outputs of the multiplexer,
various options related to the inputs or outputs and the default routing of NMEA sentences. The settings
are grouped together for the inputs and the outputs.

Figure 33

Speed

This sets the speed of each NMEA 0183 input or output. 4800 Baud is the standard speed for navigation
equipment. Some fluxgate or gyrocompasses operate at 9600 Baud to accommodate the higher
throughput of 20 headings per second or more. AIS equipment operates at 38400 Baud.

If you change the speed of In4, the speed of Out1 will be changed too. In4 and Out1 share the same
communication port inside the multiplexer and therefore always have the same speed. Out1 is generally
used to control an autopilot and should be left at 4800 Baud for this purpose.

If the Input Mode of In1 is set to SeaTalk, the speed setting for In1 is disabled and fixed to 4800 Baud.

Care should be taken when selecting other speeds than 4800 Baud with respect to possible queue
overflows. See the paragraph “Data Throughput” on page 25 for more information.

Talker ID

The multiplexer can change the Talker ID of incoming sentences. The first two characters of an NMEA
sentence represent the Talker ID, indicating which instrument (talker) has sent this sentence. Normally
you don’t need to change this and these fields can be left blank (“--”).

Changing the Talker ID of a sentence might be necessary for instance when using a GPS compass. Such a
compass often outputs a true heading sentence starting with $GPHDT. Many instruments or navigation
programs however require a true heading starting with $HE, which is the standard Talker ID for true
heading devices. By entering HE in the Talker ID field of the input connected to the GPS compass, the
incoming $GPHDT sentence will be changed into $HEHDT.

Setting a Talker ID can also be useful when similar instruments are connected to the multiplexer while
the navigation software must be able to distinguish between the data from these instruments. A
catamaran for instance could have a depth sounder in each hull, sending similar sentences to the
navigation software. Setting the Talker ID for those inputs to H1 and H2 respectively allows the software
to recognise both depth readings separately.

Enter the Talker ID in the edit box of the desired input and press the Enter to send the setting to the
multiplexer. A Talker ID may consist only of upper case characters and numbers. See the Technical
Reference section for an overview of the most commonly used Talker ID’s.

When the Talker ID is changed, the background of the edit field turns yellow to indicate that de modified
Talker ID has not yet been sent to the multiplexer. Pressing Enter will send all Talker ID’s to the
multiplexer and the background colour will return to white again. It is possible to change all Talker ID’s
first and press Enter after changing the last one. Starting at the Talker ID field of input 1, pressing the
Tab key will jump to the Talker ID of the next input.

Clicking the “Read Configuration” button will read the Talker ID settings from the multiplexer. Any
modified Talker ID’s that have not been sent to the multiplexer (yellow background) will revert to their
original values. To clear a Talker ID, simply clear the edit box(es) by selecting them with the cursor and

32

press the Del or Backspace key on your keyboard and finally press Enter. An empty Talker ID setting will
show two dashes.

To Output 1 & 2

These options allow you to set the default route from the NMEA 0183 inputs, the NMEA 2000 port and the
conversion results to the NMEA 0183 outputs. The default route as showed in Figure 33 routes all inputs
to Out2 and none to Out1. The NMEA 0183 inputs and NMEA 2000 port are always routed to the host
port. Similarly, the Host port is always routed to the NMEA 2000 port. Only filter rules can override this.

The default route is applied to an input when no specific route for an NMEA 0183 sentence exists in the
sentence filter. A match in the sentence filter always takes precedence over the default route.

Input Mode

The NMEA 0183 inputs of the multiplexer can be set to different modes besides standard NMEA, to be
able to accept “not quite standard” NMEA, plain text or SeaTalk. The following modes are supported:

NMEA: Normal NMEA processing. This is the default processing mode which checks sentences

for correct formatting. They must start with a ‘$’ or ‘!’ character and end with a
Carriage Return (CR) and a Line Feed (LF) character in that order. If a sentence
contains a checksum, the checksum of the sentence is calculated and compared with the
checksum field of the sentence. If all of the conditions above are met, the sentence is
passed. Otherwise it is rejected. This processing meets the IEC/EN60945 standard.

NMEA (ERR): Pass NMEA sentences that contain a checksum error unmodified, bypassing all further

NMEA processing and filtering. Only the default route is applied.

NMEA (CR/LF): Relaxed NMEA format checking. This will pass a sentence that is incorrectly terminated.

A sentence is considered terminated if it ends on a CR, a LF or a combination of both in
arbitrary order.

Text to NMEA: Accept a plain text string and forward it in a standard NMEA $--TXT sentence. Any

character with an ASCII value > 32 (a space) is considered to be the start of a string.
The string must end on a CR or LF and may not be longer than 61 characters. A longer
string is discarded. Only valid NMEA characters are passed. Invalid characters are
stripped from the input data.
The Total number and Sentence number fields are always set to ‘01’. The Text Identifier
field of the $MXTXT sentence contains the input number on which the text was received.
When for instance ‘Hello World’ is received on input 3, the resulting sentence will be:
$MXTXT,01,01,03,Hello World*6E.

Text to PTXT: Accept a plain text string and forward it in a $PTXT sentence. Any character with an

ASCII value > 32 (a space) is considered to be the start of a string. The string must end
on a CR or LF and may not be longer than 61 characters. A longer string is discarded. All
characters with an ASCII value from 32 to 127 are passed.

Plain Text: Accept a plain text string and forward it as a plain text string. Any character with an

ASCII value > 32 (a space) is considered to be the start of a string. The string must end
on a CR or LF and may not be longer than 61 characters. A longer string is discarded. All
characters with an ASCII value from 32 to 127 are passed. The multiplexer will always
end a forwarded string with a CR/LF pair.

SeaTalk: This option enables translation of SeaTalk® data received on In1 into NMEA 0183

sentences and NMEA 2000 PGNs (only on NMEA 2000 enabled multiplexers).
SeaTalk (often called SeaTalk1 to distinguish it from SeaTalk NG) is a proprietary
protocol developed by Raymarine and is used for data exchange between Raymarine
navigation instruments like the ST40, ST50 and ST60 series. To be able to use these
instruments with commonly available navigation programs or to feed their data into
non-Raymarine instruments, SeaTalk data needs to be translated into NMEA 0183
sentences. See the Technical Reference section for an overview of translated SeaTalk
data.
Selecting this option will automatically set the communication speed of In 1 to 4800
Baud and disable the speed setting.

33

NMEA 2000

NMEA 2000 PGN’s are converted into NMEA 0183 sentences, which receive the same processing as
NMEA 0183 sentences received on In1 to In4. They can be routed accordingly using the default route
settings and the “Sentence Filtering & Routing feature”.

NMEA Conversions

The results of NMEA conversions (see Options page, Figure 35) are available as if these NMEA 0183
sentences were received on a separate -virtual- input. They can be routed accordingly using the default
route settings and the “Sentence Filtering & Routing feature”.

Host Data

This controls if and how the data from the host interfaces is sent to both NMEA outputs. Possible options
are No, Yes or Override.

No: No data from the host is sent to the NMEA output.

Yes: Data from the host is sent to the NMEA output and mixed with data from the inputs.

Override: Data from the host is sent exclusively to the output and takes precedence over the data from

the inputs. When the host sends data to the multiplexer, no other data is sent to that output.
When the host stops sending data however, data from the inputs will be sent to the outputs
again after a time out of 10 seconds.

The Override option is very useful when sailing alternately with our without a laptop. Consider a typical
set-up as shown in Figure 34:

Figure 34

When the laptop is connected, it will receive all information from the instruments and the navigation
software, calculates the course to steer and drives the autopilot accordingly. Because the laptop is
sending NMEA data, the multiplexer routes this data exclusively to Out1. The autopilot will therefore
receive information from the laptop only.

When the laptop is not connected or the navigation software is not sending any data, the multiplexer
automatically routes the inputs to Out1, sending the data from the instruments to the autopilot. This
way, the autopilot will receive course information directly from the GPS.

Output NMEA V1.5

NMEA output 2 has an option to convert specific NMEA 0183 sentences to V1.5 format. Some older
navigation devices can only process NMEA 0183 V1.5 sentences. The major difference between
NMEA 0183 V1.5 and newer versions is an added status field at the end of specific sentences. Older
devices may have trouble reading these newer sentences. If this option is enabled, the multiplexer
removes this status field from the end of NMEA sentences ABP, BWC, BWR, GLL, RMB, RMC, VTG and
XTE.

Note: this option only works on NMEA Out2!

Wind

Comp-

pass

GPS Autopilot

Laptop

Multiplexer

In 1

In 2

In 3

USB

Out 1

34

Options

On the Options page, several operational options and NMEA 0183 conversions can be enabled.

Figure 35

Priority

This option deletes duplicate NMEA 0183 sentences received on multiple inputs. When enabled, the
multiplexer assigns a priority to incoming NMEA 0183 (and NMEA 2000) data based on the input on which
it is received. The host interfaces have the highest priority, followed by the NMEA 2000 port, NMEA 0183
In1, In2, In3 and In4 in descending order. NMEA conversion results have the same priority as the input
which received the source of the conversion.

If for instance two GPS receivers are connected to In1 and In2 and both GPS receivers send GPRMC
sentences, only those from the GPS on In1 are passed. This feature can be useful to set up a second GPS
as a backup for the main GPS.

The multiplexer only uses the Sentence Formatter (the RMC part) for comparison - the Talker ID (the GP
part) is ignored.

Another useful application of Priority is when a GPS and an AIS transponder are connected to the
multiplexer. An AIS transponder often sends sentences from its internal or connected GPS. A navigation
program will now receive GPS data from two sources that might differ in position due to GPS inaccuracy.
This will lead to navigation errors. When the AIS transponder is connected to In1 and the GPS to In2, all
the NMEA 0183 sentences from the AIS transponder are passed while duplicate NMEA 0183 sentences
(e.g. GPRMC) from the GPS are blocked. When the AIS transponder fails, GPRMC sentences from the GPS
will be passed again after an adjustable timeout.

Note that the priority system does not block an entire input, it only blocks duplicate sentences. Sentences
received from the GPS that are not received on the AIS input are passed.

The following example shows what is passed and what not: the left column in
Table 1 shows sentences from the AIS transponder on In1 and the right
column sentences from the GPS on In2. The priority feature blocks the
greyed sentence in the table.

The priority feature can store up to 50 different sentence types to determine
their priority. A time out mechanism ensures that sentences received on
lower priority inputs are passed again after an adjustable time out when their
duplicates on higher priority inputs are no longer received.

Check GPS status

Normally, the priority feature detects the absence of NMEA sentences. When the “Check GPS status”
option is enabled, it detects invalid sentences, specifically from a GPS.

When a secondary GPS is connected as a backup to the primary GPS, the primary GPS must completely
fail (stop sending data) before sentences from the secondary GPS are passed. A situation may arise
however, in which the primary GPS no longer receives a satellite signal (broken antenna, cable, etc). It
will still send NMEA 0183 position sentences to the multiplexer with the status flag set to “invalid fix”, so
the priority feature will not fall back to the secondary GPS.

AIS

(In1)

GPS

(In2)

GPRMC

GPRMC

AIVDM

GPGGA

Table 1

35

When “Check GPS status” is enabled however, the multiplexer will check the status field of the GPS
sentences, detect the invalid position fix and fall back to the secondary GPS. Sentences of which the
Status flag is checked are APB, GGA, GLL, RMA, RMB, RMC, VTG and XTE.

Time Out

This setting allows you to set the time it takes before sentences from a lower priority input are passed.

SeaTalk Priority

This sets the priority of the SeaTalk data in relation to In2 to In4. It can be either Highest (SeaTalk – In 2
– In 3 – In 4) or Lowest (In 2 – In 3 – In 4 - SeaTalk).

Channel Information

These options insert channel number information in the NMEA stream sent to the host interfaces. Channel
numbers allow distinguishing between similar data from different instruments, like two depth sounders on
the same boat.

When “STN Sentence” is enabled, each received NMEA sentence is preceded by am $MXSTN sentence to
indicate on which NMEA input the following sentence was received. The example in Figure 36 shows that
an IIGGA sentence was received on In1, a GPGGA sentence on In2, an IIGLL sentence on In1 and an
HEHDT sentence on In3.

$MXSTN,01*71
$IIGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*2E
$MXSTN,02*72
$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*39
$MXSTN,01*71
$IIGLL,5301.0061,N,00635.5479,E,143357.999,A*22
$MXSTN,03*73
$HEHDT,67.0,T*1E

The $MXSTN sentence is defined by the NMEA standard and a description can be found in the Technical
Reference at the back of this manual.

When “TAG Blocks” is enabled, the multiplexer adds an NMEA 0183 V4.0 TAG block to each sentence.
This TAG block contains a source identification parameter indicating on which input that sentence was
received. Figure 37 shows the same data as above, but with TAG blocks added.

\s:MX02-1*42\$IIGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*2E
\s:MX02-2*41\$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*39
\s:MX02-1*42\$IIGLL,5301.0061,N,00635.5479,E,143357.999,A*22
\s:MX02-3*40\$HEHDT,67.0,T*1E

See the Technical Reference section for a description of TAG blocks.

NMEA Conversions

NMEA Conversions allow you to convert specific NMEA 0183 sentences into new NMEA 0183 sentences.
The originating sentence used for the conversion is forwarded as usual but can optionally be blocked
using the sentence filter. The conversion results are available on a virtual input called “NMEA
Conversions” on the “NMEA Inputs/Outputs” page and on input C on the “Sentence Filtering & Routing”
page. They can be routed anywhere using the default route and the Sentence Filter.

Heading Magnetic <-> True (HDG/HDM <-> HDT)

If this option is enabled, the multiplexer converts magnetic and true heading in both directions. If the
multiplexer receives an HDG or HDM sentence, it will generate and output an HDT sentence (true
heading). If the multiplexer receives an HDT sentence, it will generate and output an HDG sentence.

If the HDG sentence contains a magnetic variation, it is used to calculate the true heading from the
magnetic heading. Otherwise the magnetic heading value is just copied. A variation received in an RMC
sentence is also used to calculate the true heading. The variation in an HDG sentence takes precedence
over the variation in an RMC sentence.

This option can be useful when a device needs a true heading while only a fluxgate compass is available
on board. Many satellite telephones for instance need a true heading to be able to direct their antenna to
the right communications satellite.

Figure 36

Figure 37

36

Reverse True Heading (HDT)

This option allows you to reverse the true heading in a received HDT sentence. When an HDT sentence is
received, the multiplexer generates a new HDT sentence with 180° added to the original heading. This
can be used to provide two opposing navigation stations on ferries with a heading from the same source.
Use the default route or Sentence Filter to route each sentence to a different NMEA output and only one
to the host if needed.

GPS Speed to Log Speed (VTG -> VHW)

If this option is enabled, the multiplexer will generate a VHW sentence (water speed and heading) when a
VTG sentence (course over ground and ground speed) is received. The VTG sentence is generated by a
GPS and the VHW sentence by a log. Often the paddlewheel of a log gets stuck when fouled and this
option offers a solution to substitute the log data with GPS data.

Log Speed to GPS Speed (VHW -> VTG)

This option generates a VTG sentence (course over ground and ground speed) when a VHW sentence
(water speed and heading) is received. This can be useful if a device needs a VTG sentence while only a
Log is available.

Wind: VWR <-> MWV

This option generates an MWV sentence from a VWR sentence and vice versa. Sometimes software
expects one sentence while the wind instrument generates the other. By enabling this option, ‘old’ and
‘new’ can be connected without problems.

Relative to Theoretical Wind (MWV,R -> MWV,T)

This option lets the multiplexer calculate the Theoretical Wind (often called True Wind) from the Apparent
Wind. When the multiplexer receives an MWV sentence with Apparent/Relative Wind, it will generate a
new MWV sentence with Theoretical Wind. If only VWR sentences are received, the VWR <-> MWV
option can be enabled to convert to an MWV sentence first.

GPS: RMC -> GGA

This option generates a GGA sentence when an RMC sentence is received. Some VHF radios require a
GGA sentence instead of RMC for GMDSS operation. If you have a system with a SeaTalk GPS, the
SeaTalk -> NMEA conversion only generates an RMC sentence. This option can then be used to generate
the required GGA sentence for the VHF radio.

37

Sentence Filtering & Routing

The “Sentence Filtering & Routing” feature is the most powerful feature of the MiniPlex. It allows you to
filter and route NMEA sentences based on the Address Field of an NMEA sentence (the “GPRMC” part) and
optionally reduce the rate of the sentence. Sentences can be passed or blocked, specified by input
(filtering) and they can be forwarded to specific outputs (routing). Up to 50 rules can be entered, either
manually or by capturing the NMEA sentences received by the multiplexer.

Figure 38

Each filter/routing rule in the list consists of the Address Field of an NMEA sentence, checkboxes to
specify the source inputs and destination outputs and a divisor factor to reduce the sentence rate. The
buttons on the right allow you to modify the list and to store it into the multiplexer.

List Columns

The Filter & Routing list contains the following columns:

Inputs:
1-4: NMEA 0183 inputs 1 to 4. If In1 is set to SeaTalk, the ‘1’ changes into ‘ST’
N: Input from the NMEA 2000 port

1

C: NMEA 0183 Conversion results
H: Input from the Host port

Sentence: The Address Field of an NMEA 0183 sentence. This fully specifies the type of NMEA sentence

to be filtered/routed. A ‘-’ (dash) matches any character. If for instance --GLL is entered, any
sentence that ends on GLL will match, regardless of the first two characters (the Talker ID).
A P---- will match on every proprietary sentence starting with $P.
The Sentence field must contain 5 characters.

Div: Divisor field. A number from 0 to 99 will divide the sentence rate by the number entered. If

this field contains a divisor of 5 for instance, every fifth occurrence of this sentence will be
passed.

Outputs:
1,2: NMEA outputs 1 and 2
ST: Output to SeaTalk port

2

N: Output to NMEA 2000 port

1

PC: Output to Host port.

Note1: This column is only enabled if connected to a MiniPlex-3 with an NMEA 2000 interface.

Note2: This column is only enabled if In1 is set to SeaTalk mode and the MiniPlex-3 firmware supports sending of

SeaTalk data.

Editing the list

It is important to keep in mind that all modifications and additions are made to the list loaded in MPX­Config-3, not in the multiplexer. The current list is automatically loaded from the multiplexer when you
connect to the multiplexer or when you click on the “Read Configuration” button. After editing, the list
must be stored in the multiplexer using the “Store List” button to be effective.

Clicking on a checkbox in an input or output column enables a sentence on that input or output.

38

The Sentence and Divisor fields can be edited by selecting it with the cursor. Edit mode is entered in
several ways:

● Press function key F2 on your keyboard. This enters Edit mode with the cursor at the end of the text.
Move the cursor around with the mouse or arrow keys.

● Press Enter or click with the cursor: This enters Edit mode with the text selected and the cursor at
the end. Any character or number that is typed now will erase the existing text entirely unless the
cursor is moved around with the mouse or arrow keys. This will unselect the text.

● Double-click on the entry. This enters Edit mode the same way as pressing Enter or clicking it for the
second time.

When changes are made, press Enter to confirm them or press Escape to discard any changes and exit
Edit mode.

The Technical Reference section lists commonly used Talker IDs and Sentence Formatters. This list can
be a useful aid while setting up the sentence filter.

The following buttons are available to edit the list:

Store List Stores the list from MPX-Config-3 into the multiplexer. This overwrites the list in the

multiplexer.

Capture Enables capture mode. The list will be filled automatically with NMEA 0183 sentences

currently received by the multiplexer.

Add Add a new rule. Type the desired sentence address into the edit box next to the Add

button and click on Add or press the enter key. This will enter a new rule with all inputs
and outputs disabled. The input is case-insensitive; every entered sentence address will
be converted into uppercase. The input must contain 5 characters, including dashes.
Numbers are also allowed.

Delete Delete a rule from the list in MPX-Config-3. Select the entry to be deleted by clicking on

the address in the Sentence column and click on the Delete button.

Default Action This setting determines what happens if a received sentence is not found in the

filter/routing list. It can be set to either apply the default route or to block it.

Clear List This button clears the list in MPX-Config-3 (not in the multiplexer!). To clear the list in

the multiplexer, click on the Store List button after clearing the list in MPX-Config-3.

Filling the list

The filter rules can be entered in two ways: manually and automatically. You can add individual
sentences to the list and set the desired routing information. You can also fill the list automatically with
the Capture button. All controls will be disabled during capture and the Capture button changes to Stop.
Leave the capture mode running for approximately 10 seconds. By that time, all connected instruments
will have sent NMEA sentences. Click on Stop to end the capture mode.

It is very important to realize that using capture to fill the list overrides the default routes since every
sentence is in the filter list.

It is absolutely necessary to review and modify the routing settings for each sentence after a
Capture! It is often best not to use the filter at all if you don’t need sentence-specific routing.

Use the filter with care! Simply capturing the list and storing it unmodified is useless and can
lead to unforeseen problems!

Operation

When the multiplexer receives an NMEA 0183 sentence, it searches the filter list for a match. It doesn’t
matter if this sentence is received on one of the NMEA 0183 inputs, a conversion result or a converted
NMEA 2000 PGN. They are all treated equally.

The order of the filter/routing rules in the multiplexer is exactly the same as shown in MPX-Config-3.
When a match is found, the input on which the sentence was received is checked against the input
settings (checkboxes in the “Inputs” columns) of this rule to determine whether the sentence may be
passed or not. If the input matches, the sentence is passed for further processing or conversion and
eventually it is routed to any enabled output (checkboxes in the “Outputs” column). For each sentence
received, the entire filter/routing list is scanned and a sentence may occur multiple times in the filter list.

If no match is found, the “No Match” setting determines what happens next: when set to “Default Route”,
the default routes are applied. When it is set to Block, the sentence is always blocked.

39

The default routes are set in the “Input Settings” section on the “NMEA Inputs/Outputs” page. Note that
the multiplexer will not pass any sentence if the filter list is empty and the “No Match” setting is set to
Block.

Received NMEA 0183 sentences are following a specific processing route, as shown in Figure 39 below:

Figure 39

A few important things can be seen from this figure:

• If a Talker ID is set for an input, it is applied to received NMEA sentences before the sentence filter is
applied. A filter rule must therefore contain the correct Talker ID.

• Conversions are applied after filtering. As a result, sentences that are blocked on an input will not be
converted. So if you need to convert a sentence and only want to use the conversion result only, the
originating sentence must be enabled on the receiving input and blocked on all outputs. The
conversion result needs to be enabled on the ‘C’ input and routed to the desired output.

Example

Figure 40 shows a small set of filter rules:

Figure 40

These rules have the following effect:

1. GPRMC sentences are passed from SeaTalk and routed to output 1, NMEA 2000 and to the PC.

2. HEHDT sentences are passed from input 2 and routed to NMEA 2000 and the PC. Only every 5th
sentence is passed.

3. WIMWV sentences are passed from NMEA 2000 and routed to the PC.

4. WIMTW sentences are passed from NMEA 2000 and routed to the PC.

5. VWVHW sentences are passed from SeaTalk and routed to the PC.

6. AIVDM sentences are passed from input 2 and routed to the PC.

7. WIVWR sentences are passed from a conversion and routed to output 1.

The default route is applied to sentences that are not in the filter list.

Talker

ID

Conversions

GPS Status

Check

Sentence

Filter

(Inputs)

Priority

NMEA

In

Routing

(Outputs)

NMEA

Out

40

NMEA 2000

The NMEA 2000 page currently only shows two options regarding processing of PGN’s.

Show unknown PGN’s

Normally, unknown PGN’s are simply ignored by the multiplexer. When this option is enabled, these
unknown PGN’s are converted into an $MXPGN sentence. This is an NMEA 0183 sentence containing the
PGN number, an attribute field and the binary data of the PGN, all represented as hexadecimal ASCII
field. Such a sentence looks like this:

$MXPGN,01F112,2807,FC7FFF7FFF168012*11

This option can be useful when navigation software needs to read PGN’s for which no NMEA 0183
sentence exists. Such PGN’s could contain battery or alternator status, engine data or an electrical switch
position. Converting these PGN’s to an $MXPGN sentence allows developers to easily read NMEA 2000
data with existing NMEA 0183 sentence parsers.

Show all PGN’s

When this option is enabled, all conversions from NMEA 2000 to NMEA 0183 sentences is disabled and
every received NMEA 2000 PGN is converted into an $MXPGN sentence. This allows software on a PC to
read and decode all NMEA 2000 PGN’s.

It is also possible to send an $MXPGN sentence to the multiplexer. The multiplexer will then convert this
to an NMEA 2000 PGN and send it onto the NMEA 2000 network.

The Technical Reference in the back of this manual contains a detailed description of the $MXPGN
sentence and how to use it.

One $MXPGN sentence is always transmitted by the multiplexer: $MXPGN,00EE00,…. This sentence
contains the NMEA 2000 Address Claim message, which is transmitted by every device on the NMEA 2000
network for network address management. Future versions of MPX-Config-3 will use this message to
show all devices present on the NMEA 2000 network.

Figure 41

41

Firmware Update

Firmware updates with new features or bug fixes will be available through our web site. These firmware
files can be downloaded to your computer and loaded into the multiplexer using option “Update MiniPlex
Firmware…” from the File menu.

Procedure

Make sure the multiplexer is connected to your computer via USB or Ethernet, start MPX-Config-3 and
connect to the multiplexer.

Download the firmware update and unpack the .zip file. Remember in which folder you stored the .mpx
file.

Choose “Update MiniPlex Firmware…” from the File menu.

Using the file dialog, locate and select the firmware image file. When you have selected the file and
clicked on OK, the update process is started. The image file’s integrity and version is checked first before
initiating the download procedure in the multiplexer.

When the download is started, the red LED on the multiplexer will be lit continuously while the green LED
blinks on reception of data from the computer. MPX-Config-3 will show a progress indicator during the
update process. When the update is complete and successful, a message will show “The firmware update
was successful”.

Any errors that occur during the process will be shown. It is important to make a note of the error
message when asking for support. See “Firmware Update Error messages“ for an explanation of the error
messages.

Whenever the update process aborts, the multiplexer will start outputting “$PSMDLDR…” sentences. This
indicates that no firmware is loaded and the multiplexer waits for a new firmware update. Just try
updating again until the process is successfully finished.

Sometimes the communication during the firmware update times out and the update is aborted with an
error message. This time out can be caused by delays in the communication drivers that are part of
Windows. These time outs happen frequently when software is running which communicates with other
serial devices.

When such a time out occurs, the MiniPlex has no firmware loaded and the internal loader keeps sending
$PSMDLDR… sentences, indicating that it waits for a firmware upload. Just try updating again until the
process is successful. Sometimes it helps to try the update on a different computer.

42

Mounting

The multiplexer is not waterproof. It should be mounted at a dry place such as behind the instrument
panel on a flat surface.

Make sure there is enough space around the multiplexer to connect the NMEA 0183 wiring at the bottom,
the NMEA 2000 connector on the left side and USB/Network connector on the right side of the housing.

43

Technical Reference

NMEA 0183 Glossary

This glossary lists the most common Talker ID’s and Sentence Formatters in alphabetical order.

Talker ID’s

AG Autopilot (general)
AP Autopilot (magnetic)
AI Automatic Identification System
CD Communications: Digital Selective Calling (DSC)
CR Data receiver
CS Satellite
CT Radio telephone (MF/HF)
CV Radio telephone (VHF)
CX Scanning receiver
DE Decca navigator
DF Direction finder
EC Electronic chart systems (ECS)
EI Electronic chart display and information system (ECDIS)
EP Emergency position indicating radio beacon (EPIRB)
ER Engine room monitoring systems
GP Global Positioning System (GPS)
GL GLONASS receiver
GN Global navigation satellite system (GNSS)
HC Heading sensors: compass, magnetic
HE gyro, north seeking
HN gyro, non-north seeking
II Integrated instrumentation
IN Integrated navigation
LC Loran, Loran-C
MX Multiplexer
P Proprietary sentence
RA Radar and/or radar plotting
SD Sounder, depth
SN Electronic positioning system, other/general
SS Sounder, scanning
TI Turn rate indicator
VD Velocity sensors: doppler, other/general
VM speed log, water, magnetic
VW speed log, water, mechanical
VR Voyage data recorder
YX Transducer
ZA Timekeepers: atomic clock
ZC chronometer
ZQ quartz
ZV radio updated
WI Weather instruments

Sentence formatters

AAM Waypoint arrival alarm
ACK Acknowledgement alarm
ALM GPS almanac data
ALR Set alarm state
APB Heading/track controller (Autopilot) sentence B
BEC Bearing and distance to waypoint, dead reckoning
BOD Bearing, origin to destination
BWC Bearing and distance to waypoint
BWR Bearing and distance to waypoint, rhumb line
BWW Bearing, waypoint to waypoint
DBT Depth below transducer
DCN DECCA position
DPT Depth
DSC Digital selective calling information

44

DSE Expanded digital selective calling
DSI DSC transponder initialise
DSR DSC transponder response
DTM Datum reference
FSI Frequency set information
GBS GNSS Satellite fault detection
GGA Global positioning system fix data
GLC Geographic position, LORAN-C
GLL Geographic position, latitude/longitude
GNS GNSS fix data
GRS GNSS range residuals
GSA GNSS DOP and active satellites
GST GNSS pseudo range error statistics
GSV GNSS satellites in view
HDG Heading, deviation and variation
HDT Heading, true
HMR Heading monitor – receive
HMS Heading monitor – set
HSC Heading steering command
HTC Heading/track control command
HTD Heading/track control data
LCD LORAN-C signal data
MLA Glonass almanac data
MSK MSK receiver interface
MSS MSK receiver signal status
MTW Water temperature
MWD Wind direction and speed
MWV Wind speed and angle
OSD Own ship data
PGN NMEA 2000 PGN data
RMA Recommended minimum specific LORAN-C data
RMB Recommended minimum navigation information
RMC Recommended minimum specific GNSS data
ROT Rate of turn
RPM Revolutions
RSA Rudder sensor angle
RSD Radar system data
RTE Routes
SFI Scanning frequency information
STN Multiple data ID
TLB Target label
TLL Target latitude and longitude
TTM Tracked target message
TXT Text transmission
VBW Dual ground/water speed
VDR Set and drift
VHW Water speed and heading
VLW Distance travelled through the water
VPW Speed, measured parallel to wind
VTG Course over ground and ground speed
WCV Waypoint closure velocity
WNC Distance, waypoint to waypoint
WPL Waypoint location
XDR Transducer measurements
XTE Cross-track error, measured
XTR Cross-track error, dead reckoning
ZDA Time and date
ZDL Time and distance to variable point
ZFO UTC and time from origin waypoint
ZTG UTC and time to destination waypoint

45

Supported NMEA 2000 PGN’s

PGN
Decimal

PGN
Hex

Description

TX

RX

059392

E800

ISO Acknowledge

"

"

059904

EA00

ISO Request

"

"

060928

EE00

ISO Address Claim

"

"

126996

1F014

NMEA Product Information

"

126992

1F010

System Time

"

"

127237

1F105

Heading/Track Control

"

"

127245

1F10D

Rudder

"

"

127250

1F112

Vessel Heading

"

"

127251

1F113

Rate of Turn

"

"

127258

1F11A

Magnetic variation

"

"

128259

1F503

Speed, Water referenced

"

"

128267

1F50B

Water Depth

"

"

128275

1F513

Distance Log

"

"

129025

1F801

Position, Rapid Update

"

"

129026

1F802

COG & SOG, Rapid Update

"

"

129029

1F805

GNSS Position Data

"

"

129033

1F809

Local Time Offset

" 129283

1F903

Cross Track Error

"

"

129284

1F904

Navigation Data

"

"

130306

1FD02

Wind Data

"

"

130310

1FD06

Environment

"

"

130311

1FD07

Environment

"

"

130312

1FD08

Temperature

"

"

130313

1FD09

Humidity

"

130314

1FD0A

Actual Pressure

" 130316

1FD0C

Temperature, extended range

"

46

Translated SeaTalk datagrams

When the SeaTalk translation is enabled, the following datagrams are translated into NMEA sentences:

SeaTalk

NMEA

Description

00

DBT

Depth below transducer

10

MWV

Wind angle, (10 and 11 combined)

11

MWV

Wind speed, (10 and 11 combined)

20

VHW

Speed through water, includes heading when
present

21

VLW

Trip mileage (21 and 22 combined)

22

VLW

Total mileage (21 and 22 combined)

23

MTW

Water temperature

25

VLW

Total and Trip mileage

26

VHW

Speed through water, includes heading when
present

27

MTW

Water temperature

50

---

GPS latitude, value stored

51

---

GPS longitude, value stored

52

---

GPS speed over ground, value stored

53

RMC

Course over ground. RMC sentence is
generated from stored values from other GPS
related datagrams.

54

---

GPS time, value stored

56

---

GPS date, value stored

58

---

GPS lat/long, values stored

89

HDG

Magnetic heading, including variation (99)

99

---

Magnetic variation, value stored

The table shows that not all datagrams result in an NMEA 0183 sentence. Some datagrams are only used
to retrieve data, which is combined with data from other datagrams to be able to create one NMEA 0183
sentence.

When the option 4 is enabled using the $PSMDOP sentence, unlisted datagrams are translated into a
proprietary NMEA sentence with the following format:

$PSMDST,aa,bb,cc,dd…*hh<CR><LF>

aa,bb,cc,dd… represent the hexadecimal value of the bytes from the received SeaTalk datagram.

47

Firmware Update Error messages

During a firmware update, the following warnings or error messages may be displayed:

The firmware update failed

This message appears when the overall update process failed without any other error message. It is
shown when the updated multiplexer firmware does not report a version message after start-up.

Not a valid firmware file

The file you are trying to open is not a valid firmware file. A firmware file not only ends with an “.mpx”
extension, it also contains a distinct signature that must be present. This prevents you from
accidentally loading the wrong file into the multiplexer.

Unsupported firmware file version

The firmware file version is not supported by MPX-Config-3. Currently, there is only one firmware file
version but it is not unlikely that in the future new version are developed which require an update of
MPX-Config-3.

Firmware file is corrupt

The firmware file is damaged, possible due to an error during download from our website.

The version of the firmware file is lower than the version of the multiplexer. Do you really
want to proceed?

You are trying to update the firmware in the multiplexer with an older version. This is just a warning
and very well possible to do.

Bootloader initialisation failed

When MPX-Config-3 starts the update process, a small program called the Bootloader must be started
in the multiplexer. This message tells you that the bootloader could not be started. This can happen
when you try to update the multiplexer while navigation instruments are connected and sending lots
of NMEA data to the multiplexer. This can interfere with starting the update process. Disconnect or
power down the instruments to prevent this problem.

Firmware file does not match with the multiplexer type

Most firmware files will be compatible with all types of multiplexers. It is however possible that special
firmware is made available which only runs on a specific type of multiplexer. If this message appears,
you apparently are trying to update using a firmware file that is not suitable for your type of
multiplexer.

Bootloader: Erase command timeout

An error occurred when the bootloader tried to erase the old firmware.

Bootloader: Encryption command timeout

The bootloader did not respond to the Encryption command sent by MPX-Config-3.

Bootloader: Programming timeout

There was an error during programming a section of the firmware image.

Bootloader: CRC command timeout

The bootloader failed to calculate the checksum of the newly loaded firmware image.

Bootloader: CRC error

The calculated checksum of the newly loader firmware image does not match the checksum if the
image file. Apparently there was a communication error between MPX-Config-3 and the multiplexer.
You can try to update again.

Invalid response from bootloader

The bootloader returned an unknown response to a command from MPX-Config-3.

48

Standard NMEA 0183 Sentences

The following standard NMEA 0183 sentences are used by the MiniPlex-3.

$MXSTN – Multiple Data ID

When STN sentences are enabled ($PSMDOP, option 11), the multiplexer transmits a $MXSTN sentence
before every NMEA sentence that is sent from the host interface.

Format: $MXSTN,xx*hh<CR><LF>
xx: Input number, 00 to 06.

The Input Number indicates on which the following NMEA sentence was received:

00: Internally generated responses ($PSMD sentences)
01: NMEA 0183 Input 1 or SeaTalk
02: NMEA 0183 Input 2
03: NMEA 0183 Input 3
04: NMEA 0183 Input 4
05: NMEA 2000
06: Conversion results

$MXPGN – NMEA 2000 PGN Data

This sentence transports NMEA 2000 Single Frame messages over NMEA 0183. The MiniPlex will output
this sentence with Talker ID “MX”. When sent to the MiniPlex, the Talker ID is ignored unless a Filter Rule
exists for this sentence.

Format: $--PGN,pppppp,aaaa,c--c*hh<CR><LF>

pppppp: PGN of the NMEA 2000 message, 3 byte hexadecimal number. If the PGN is non-global, the

lowest byte contains the destination address.

aaaa: Attribute Word, 2 byte hexadecimal number. This word contains the priority, the DLC code and

then source/destination address of the message, formatted as shown below:

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

┌───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┐
│ S │ Priority │ DLC │ Address │
└───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┘

S: Send bit. When an NMEA 2000 message is received, this bit is 0.

To use the $MXPGN sentence to send an NMEA 2000 message, this bit must be set to

1.

Priority: Message priority. A value between 0 and 7, a lower value means higher priority.

DLC: Data Length Code field, contains the size of the message in bytes (1..8) or a Class 2

Transmission ID (9..15).

Address: Depending on the Send bit, this field contains the Source Address (S=0) or the

Destination Address (S=1) of the message.

c--c: Data field of the NMEA 2000 message, organized as one large number in hexadecimal notation

from MSB to LSB. This is in accordance with “NMEA 2000 Appendix D”, chapter D.1, “Data
Placement within the CAN Frame”.

The size of this field depends on the DLC value and can be 1 to 8 bytes (2 to 16 hexadecimal
characters).

NMEA 2000 Reception

When the multiplexer converts an NMEA 2000 message into an $MXPGN sentence, the S bit in the
Attribute field will be 0 and the Address field contains the source address of the message. The destination
address of the message is either global or contained in the lower byte of the PGN, in accordance with the
NMEA 2000/ISO specification.

NMEA 2000 Transmission

A $--PGN sentence sent to the multiplexer will be converted to an NMEA 2000 message if the S bit in the
Attribute field is 1.

The Address field is the Destination Address of the NMEA 2000 message. The Source Address of the
message will be the address the multiplexer has acquired during the Address Claim Procedure. If a global
PGN is used, the contents of the Address field will be ignored. A non-global PGN can be sent globally by
setting the Address field to 0xFF.

49

The Destination Address of a non-global PGN can also be specified by loading it into the lower byte of the
PGN. The Address field of the Attribute word must be set to 0x00 for this.

The DLC field must be set to the size of the Data field (1 to 8 bytes) and the actual size of the Data field
must match with the DLC. If the DLC field us used as a Class 2 Transmission ID (9..15), the size of the
Data field must be 8 bytes/16 characters. If any of these conditions is not met, the message will not be
transmitted.

For quick transmission of an NMEA 2000 message, the Attribute field of the $--PGN sentence may be
omitted. In this case, the following values for the Attribute will be assumed:

S: 1
Priority: 7
DLC: Set automatically from the size of the Data field (c—c) field.
Address: 0. The Destination Address of the message will be contained in the PGN field (pppppp).

Examples

A received PGN 127250 (hex: 1F112, Vessel Heading) will be converted into the following $MXPGN
sentence:

$MXPGN,01F112,2807,FC7FFF7FFF168012*11

The Attribute word shows a received frame (S=0), with priority 2, it is 8 bytes and the Source Address is
0x07.

To tranmit PGN127250, the following $--PGN sentence must be sent to the multiplexer:

$MXPGN,01F112,A800,FC7FFF7FFF168012*65

In this example, the Address field of the Attribute field is ignored and set to 0x00 because PGN 127250 is
a Global PGN.

An ISO Request (PGN 059904) can be transmitted in the following ways:

$MXPGN,00EA00,F309,01F016*68
$MXPGN,00EA09,,01F016*1D

In both cases, this message is sent to Destination Address 0x09. In the first sentence, the Destination
Address is specified in the Attribute word, the second sentence has it embedded in the PGN field.

50

Proprietary NMEA 0183 Sentences

The MiniPlex multiplexers are configured with proprietary NMEA sentences that can be sent to the
multiplexer through the host interface. These will be called commands.

The multiplexer can also output proprietary NMEA sentences on a host interface to output status
information or a response to a received proprietary NMEA sentence.

The multiplexer also outputs some standard NMEA sentences. These sentences all start with ‘MX’, which
is the talker ID for a multiplexer as defined by the NMEA standard.

The host interface is the port that connects to a computer, laptop, smartphone or tablet by means of RS­232, USB, Bluetooth, WiFi or Ethernet. A MiniPlex can have more than one host interface. When the
multiplexer outputs something on a host interface, it is sent to all host interfaces simultaneously. All host
interfaces operate equally and have equal priority.

All MiniPlex proprietary sentences have the following format:

$PSMDxxx,a,b,…*hh<CR><LF>

$P: Start of a proprietary sentence as dictated by the NMEA standard
SMD: ShipModul manufacturer mnemonic
xxx: One, two- or three-character sentence formatter
a,b,…: Optional fields
*hh: Optional checksum field
<CR><LF>: Cariage Return and Line Feed characters that terminate the sentence

Unless specified otherwise, fields are optional and may be skipped when no change is required. For
instance, a $PSMDCF,C,,,,1 sentence only enables Channel Numbers. The preceding fields are skipped
(,,,,) and the trailing fields are omitted.

For ease of manual configuration, these sentences do not require a checksum. If the sentence has a
checksum however, it is checked and the sentence is rejected on a checksum failure. Sentences output
by the multiplexer always contain a checksum. Checksums are denoted with *hh in the descriptions
below.

Sentences that are used to both set and retrieve a configuration setting have a Sentence Status field.
This field is the first field of the sentence and can be one of the following:

C: the sentence was a configuration command
R: the sentence was a response to a command

A configuration command is sent to the multiplexer to change a setting. A response is sent by the
multiplexer to report a setting.

Unless specified otherwise, all command sentences return a response with their settings when sent
without parameters.

A command sentence with its Sentence Status field set to ‘R’ is ignored by the multiplexer.

Example

The $PSMDID sentence controls the Talker ID settings of the multiplexer. When $PSMDID is sent to the
multiplexer, it will report with the current Talker ID settings with:

$PSMDID,R,aa,bb,cc,dd,ee*hh

To set the change the Talker ID settings, send the following sentence:

$PSMDID,C,aa,bb,cc,dd,ee

51

$PSMDC – Get Configuration record

This command outputs all configuration settings at once. When $PSMDC is sent to the multiplexer, it
responds with a $PSMDC sentence with the following format:

Format: $PSMDC,x,c--c*hh<CR><LF>

x : Configuration record number

c--c: Configuration record data, 64 hexadecimal characters representing a block of 32 bytes.

$PSMDN – Set NMEA 2000 Configuration

This command is used to set NMEA 2000 configruation parameters and has several sub-commands. When
issued without any parameters, the multiplexer will output all NMEA 2000 configuration settings with a
series of PSMDN,R… sentences.

Format: $PSMDM,a,c,x,y,…*hh<CR><LF>

a: Sentence Command/Status flag:

R = sentence is a response with current settings
C = sentence is a command to change settings
Q = Request PGN 60928 (Address Claim) from all devices

c : Sub-command

x,y,…: Parameters

The following sub-commands are defined:

N: Set the network parameters:

$PSMDN,a,N,x,y,z*hh<CR><LF>

x: Source Address, 0..251

y: Device Instance, 0..255
z: System Instance, 0..15

$PSMDCF – Set Configuration

This sentence sets various configuration settings of the multiplexer.

Format: $PSMDCF,a,b,t*hh<CR><LF>

a: Sentence Status flag:

R = sentence is a response with current settings
C = sentence is a command to change settings

b: Baudrate selector for the RS-232 interface (ignored when no RS-232 port present):

0 = 4800 Baud
1 = 9600 Baud
2 = 19200 Baud
3 = 38400 Baud
4 = 57600 Baud
5 = 115200 Baud

t: Priority Timeout (in seconds):

0 = 1
1 = 2
2 = 3
3 = 5
4 = 10
5 = 30

$PSMDDR – Set Default Route

This sentence specifies the default route from the NMEA inputs to the NMEA outputs and from the host
interface to the NMEA outputs. Any route set by the FL sentence overrides the standard route.

Format: $PSMDDR,a,xx,b,yy,c*hh<CR><LF>

a: Sentence Status flag:

R = sentence is a response with current settings
C = sentence is a command to change settings

xx: Input field for NMEA Out1. This is a hexadecimal number where each bit represents an NMEA

input. The following bits are defined:

52

0: NMEA In 1

1: NMEA In 2
2: NMEA In 3
3: NMEA In 4
4: NMEA 2000
5: NMEA Conversions

When a bit is 1, the input is routed to output 1, otherwise the input is not routed.

b: Host data to NMEA Out1:

0: Host data is not routed
1: Host data is routed
2: Host data is routed and overrides data from the inputs. A time out mechanism will route data
from the inputs when no data from the host is received.

yy: Input field for NMEA Out2. This is a hexadecimal number where each bit represents an NMEA

input. The following bits are defined:

0: NMEA In 1

1: NMEA In 2
2: NMEA In 3
3: NMEA In 4
4: NMEA 2000
5: NMEA Conversions

When a bit is 1, the input is routed to output 1, otherwise the input is not routed.

c: Host data to NMEA Out2:

0: Host data is not routed
1: Host data is routed
2: Host data is routed and overrides data from the inputs. A time out mechanism
will route data from the inputs when no data from the host is received.

$PSMDFL – Set Filter Rules

This sentence specifies a filter and routing rule that is applied on every incoming NMEA sentence. Filter
rules are specified using the address field of an NMEA sentence. For each filter rule, the inputs on which
the sentence may be received must be specified. Optionally, a divisor and an output routing field can be
added.

Sentences for which no rule exists are passed or blocked, depending on the filter mode set by field ‘f’ of
the CF sentence.

Format: $PSMDFL,a,ccccc,xx,dd,yy*hh<CR><LF>

a: Sentence Status flag:

R = sentence is a status report of current settings
C = sentence is a command to change settings

ccccc: Address field of the filter rule (e.g. ‘GPRMC’, ‘IIMWV’, etc). This field may contain wildcard

characters (‘-’). For instance, ‘GP---’ will apply to all sentences starting with ‘GP’. Similarly, ‘—
MWV’ will apply to all sentences ending on ‘MWV’ regardless of the Talker ID.
Multiple filter rules with the same address field may be entered to route similar sentences form
different inputs to different outputs.

xx: Input field. This is a hexadecimal number where each bit represents an NMEA input. The

following bits are defined:

0: NMEA In 1
1: NMEA In 2
2: NMEA In 3
3: NMEA In 4
4: NMEA 2000
5: NMEA Conversions
6: Host input

When a bit is 1, the sentence is forwarded, otherwise the sentence is blocked from that input.

dd: Optional divisor factor (0..99). The rate or frequency of a sentence is divided by this number to

reduce the number of sentences over time. If for instance a divisor of 6 is specified, only every
6th occurrence of this sentence is passed.

yy: Optional routing field. This is a hexadecimal number where each bit represents an output. The

following bits are defined:

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0: NMEA Out1
1: NMEA Out2
2: SeaTalk bus
3: NMEA 2000
4: Wireless output
5: Host output

When a bit is 1, the sentence is routed to that output.
When this field is omitted, a default of ‘C0’ is assumed, routing the specified sentence to all the
Host and Wireless output only.

hh: Optional checksum

An FL sentence with the word DELETE in the ‘ccccc’ field erases all rules. An FL sentence with only a
‘ccccc’ field will erase that entry. The filter accepts duplicate entries with the same ‘ccccc’ field to allow
separate routes from inputs to outputs.

Example: $PSMDFL,C,HEHDT,18,5,05<CR><LF>

This sentence specifies a rule for all sentences that have ‘HEHDT’ in the address field. It only passes
HEHDT sentences from inputs 3 and 4, the rate is lowered by a factor of 5 and the sentence is routed to
NMEA Out1 and the host only.

When the filter list is requested, the multiplexer responds by sending FL sentences, one for each list
entry. An empty FL sentence marks the end of the list.

Example response:

$PSMDFL,R,GPRMC,19,0,0F*4A<CR><LF>
$PSMDFL,R,GPGGA,18,0,0F*56<CR><LF>
$PSMDFL,R,--VWT,02,5,01*50<CR><LF>
$PSMDFL,R,GPGSV,10,0,04*55<CR><LF>
$PSMDFL,R*2C<CR><LF>

The sentences may not be dumped as one contiguous block. In case of much NMEA data, they may be
interspersed with other NMEA sentences.

$PSMDID – Set Talker ID

This sentence sets a Talker ID translation for a specific input. If a Talker ID is specified, the original
Talker ID of the sentences received on that input is replaced by the specified one, before sending the
sentence to the host.

Format: $PSMDID,a,aa,bb,cc,dd,ee,ff*hh<CR><LF>

a: Sentence Status flag:
R = sentence is a response with current settings
C = sentence is a command to change settings

aa: Talker ID for input 1/SeaTalk
bb: Talker ID for input 2
cc: Talker ID for input 3
dd: Talker ID for input 4
ee: Talker ID for NMEA 2000 input
ff: Talker ID for conversion results
hh: optional checksum

An empty field clears the ID and disables the translation for that specific channel.

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$PSMDIN – Input options

Set the operating mode of an NMEA input.

Format: $PSMDIN,a,x,x,x,x

a: Sentence Status flag:

R = sentence is a response with current settings
C = sentence is a command to change settings

x: Operating mode field for input 1 to 4:

0: Normal NMEA processing.

1: Pass NMEA sentences containing an erroneous checksum unmodified, bypassing all further

NMEA processing.

2: Relaxed NMEA format checking. Normally the multiplexer only passes sentences when they are

correctly formatted: starting with a ‘$’ or a ‘!’ and ending on a CR/LF pair.
When this mode is selected, an NMEA sentence will be passed if it starts with a ‘$’ or a ‘!’ and
ends on a CR or a LF or a combination of both in arbitrary order.
A sentence with a checksum error is blocked.

3: Accept plain text strings as input and forward them in $MXTXT sentences. Any character with

an ASCII value > 32 (a space) is considered to be the start of a string. The string must end on
a CR or LF and may not be longer than 61 characters. A longer string is discarded. Only valid
NMEA characters are passed. Invalid characters are stripped from the input data.
The Total number and Sentence number fields are always set to ‘01’. The Text Identiefier field
of the $MXTXT sentence contains the input number on which the text was received. When for
instance ‘Hello World’ is received on input 3, the resulting sentence will be:
$MXTXT,01,01,03,Hello World*6E

4: Accept plain text strings as input and forward them in $PTXT sentences. Any character with an

ASCII value > 32 (a space) is considered to be the start of a string. The string must end on a
CR or LF and may not be longer than 61 characters. A longer string is discarded. The
multiplexer will always end a forwarded string with a CR/LF pair.
All characters with an ASCII value from 32 to 127 are passed.

5: Accept plain text strings as input and forward them as plain text. Any character with an ASCII

value > 32 (a space) is considered to be the start of a string. The string must end on a CR or
LF and may not be longer than 61 characters. A longer string is discarded. The multiplexer will
always end a forwarded string with a CR/LF pair.
All characters between from ASCII 32 to 127 are passed.

6: SeaTalk to NMEA conversion on input 1 only. When this mode is selected, the $PSMDOP

response will show option 3 enabled. Any other mode (0..4) will clear both SeaTalk options in
the $PSMDOP response.

$PSMDLDR – Loader message

This sentence is output by the bootloader on the host interface. It contains the loader version and
multiplexer ID. The loader will wait for a special key during 0.2s after sending this sentence. When no
key is received, the multiplexer application code is started. If no application code is found, the loader will
continue sending this sentence.

Format: $PSMDLDR,xx,v.v,zzz

xx: Hardware ID of the multiplexer (a hexadecimal number)
v.v: Bootloader version number
zzz: Hardware name of the multiplexer

The following hardware ID’s and names are defined:

10: MPX-3S
11: MPX-3U
12: MPX-3E
13: MPX-3UW
90: MPX-3S-N
91: MPX-3U-N
92: MPX-3E-N
93: MPX-3UW-N

Example: $PSMDLDR,91,2.0,MPX-3U

This multiplexer has a MPX-3U board with an NMEA 2000 interface and the bootloader is version 2.0.

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$PSMDOP – Set Options

This sentence is used to enable or disable various options.

Format: $PSMDOP,a,o,e*hh<CR><LF>
or: $PSMDOP,a,xxxxxxxx*hh<CR><LF>

a: Sentence Status flag:

R = sentence is a response with current settings
C = sentence is a command to change settings

o: option number

e: 0 = off/disable

1 = on/enable

xxxxxxxx: all options at once as a 32 bit hexadecimal number. Each bit represents an option where bit 0

is option 0, bit 1 is option 1 etc.

Example: $PSMDOP,C,6,1<CR><LF> (enables option 6)
$PSMDOP,C,00000021<CR><LF> (enables options 5 and 0)

The following options are defined:

0: Enable Priority

1: Enable highest priority for SeaTalk data. Only effective when Priority and SeaTalk translation are

enabled.

2: Test GPS status field for priority check. When enabled, the status field of a GPS related sentence is

checked. When the data is invalid, the sentence is discarded to allow the Priority feature to pass GPS
data from a lower priority input.

3: Enable SeaTalk to NMEA translation. This will also be reflected in the $PSMDIN response: input 5 will

report SeaTalk mode.

4: Convert SeaTalk datagrams into $PSMDST,xx,xx,… sentences. Datagrams are only converted if they

are not translated into NMEA. When option 3 is enabled, only unknown datagrams are converted,
otherwise all datagrams are converted. . This will also be reflected in the $PSMDIN response: input 5
will report SeaTalk mode.

5: Generate VWR sentence from SeaTalk wind data. The default is to generate an MWV sentence.

6: Heading translation. When a magnetic heading sentence (HDM or HDG) is received, the multiplexer

generates a true heading sentence (HDT). The heading is corrected for magnetic variation if this field
is available in the HDG or HDM sentence.
When a True heading (HDT) is received, the multiplexer generates an HDM sentence.

7: Velocity translation. Generate a log sentence (VHW) from a GPS speed sentence (VTG). This is the

opposite translation of option 16.

8: Wind translation. When a VWR sentence is received, an MWV,R is generated. Reception of an MWV

sentence results in either a VWR or a VWT sentence, depending on the R or T flag in de MWV
sentence.

9: Filter Block. Block sentences that are not in the Filter & Routing list. The default is to pass sentences

that are not in the list.

10: Reverse heading. When enabled, a new HDT sentence is generated from an incoming HDT sentence

with the heading reversed by 180 degrees. Use the Sentence Filter to route the original and new HDT
sentences to different outputs.

11: Output channel information with STN sentences. When enabled, the multiplexer transmits an STN

sentence before each individual sentence to indicate on which input this sentence was received.

12: Output channel information with TAG Blocks. . When enabled, the multiplexer transmits a TAG Block

before each individual sentence to indicate on which input this sentence was received.

13: Enable conversion from NMEA 0183 V3.0 to V1.5 sentences for NMEA Out2. The following sentences

are converted: APB, BWC, BWR, GLL, RMB, RMC, VTG, XTE and ZDL.

14: Generate theoretical wind speed from apparent wind speed. This options generates an MWV,T

sentence. The necessary SOG is extracted from received RMC or VTG sentences.
This option can be used in conjunction with option 8, to first convert VWR to MWV,R and then to
MWV,T

15: Position translation. Generate a GGA sentence when an RMC sentence is received.

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16: Velocity translation. Generate a VTG sentence when a VHW sentence is received. This is the opposite

translation of option 7.

30: Output unknown NMEA 2000 PGN’s as an $MSPGN sentence.

31: Output all NMEA 2000 PGN’s as an $MSPGN sentence.

When a PSMDOP sentence without any parameters is sent, the multiplexer returns an OP sentence with a
32 bit hexadecimal number. Each bit represents an option where bit 0 is option 0, bit 1 Is option 1 etc.

Format: $PSMDOP*hh<CR><LF>

Response: $PSMDOP,R,xxxxxxxx*hh<CR><LF>

$PSMDOV – Overflow

In case of a queue overflow (blinking red LED on the multiplexer), an overflow sentence is output on the
host interface, to indicate on which input queue the overflow occurred:

Format: $PSMDOV,xx*hh<CR><LF>

xx: Hexedecimal field. The folliwing bits indicate on which input queue the overflow occurred:

0: NMEA In 1
1: NMEA In 2
2: NMEA In 3
3: NMEA In 4
4: NMEA 2000

$PSMDRESET – Reset the multiplexer

This sentence resets the multiplexer and starts the bootloader. When a ‘1’ is given as parameter, the
factory settings of the multiplexer are restored.

Format: $PSMDRESET,x*hh<CR><LF>

x: Optional parameter to indicate an action while resetting
1: restore the multiplexer to its factory settings

After a reset, the multiplexer outputs a LDR sentence and a VER sentence on the host interface.

$PSMDSP – Set Speed

This sentence sets the baudrate of the NMEA inputs and outputs.

Format: $PSMDSP,a,b,c,d,e,f,g[*hh]<CR><LF>

The following fields are defined for setting the various inputs and outputs:

a: Sentence Status flag:

R = sentence is a response with current settings
C = sentence is a command to change settings

b: NMEA In 1
c: NMEA In 2
d: NMEA In 3
e: NMEA In 4/Out 1
f: NMEA Out 2
g: RS-232 host port (ignored on multiplexers without RS-232 host port)

Valid field values are:

0 = 4800 Baud
1 = 9600 Baud
2 = 19200 Baud
3 = 38400 Baud
4 = 57600 Baud
5 = 115200 Baud (field e and f only)

Field ‘e’ is ignored when SeaTalk translation is enabled with the CF sentence.

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TAG Block

When TAG Blocks are enabled ($PSMDOP, option 12), the multiplexer adds a TAG block to every NMEA
sentence that is sent from the host interface. This TAG block has one source parameter, containing the UI
of the multiplexer and the input the sentence was received on. It has the following format:

\s:UI-x*hh\

where UI is the Unique Identifier of the multiplexer and ‘x’ is a digit representing the input number.

0: Internally generated responses ($PSMD sentences)
1: NMEA 0183 Input 1 or SeaTalk
2: NMEA 0183 Input 2
3: NMEA 0183 Input 3
4: NMEA 0183 Input 4
5: NMEA 2000
6: Conversion results

If no UI is specified with the PSMDUI sentence, “MXnn” is sent, where “nn” are the last two digits of the
serial number of the multiplexer.

A heading sentence received on input 1 will be sent to the host as

\s:MX01-1*1E\$HEHDT,23.5*37<CR><LF>

$PSMDUI – Set Unique Identifier

Sets the Unique Identiefier (UI) of the multiplexer. This UI is sent as source parameter in TAG blocks sent
by the multiplexer.

Format: $PSMDUI,a,c--c*hh<CR><LF>

a: Sentence Status flag:

R = sentence is a response with current settings
C = sentence is a command to change settings

c--c: Unique Identifier, 15 character maximum. If this field exceeds the maximum character count, is

not present or empty, the UI is reset to “MXnn” where “nn” are the last two digits of the serial
number of the multiplexer.

$PSMDVER – Get Version

This sentence retrieves version information from the multiplexer.

Format: $PSMDVER

The multiplexer responds with the following version sentence:

$PSMDVER,1.9.1,MiniPlex-3USB-N2K,39000943,A013*hh<CR><LF>

1.9.1: firmware version number
MiniPlex-3USB-N2K: multiplexer name
39000943: serial number

A013: Multiplexer capabilities. This is a 4 digit, 16-bit field represented as a hexadecimal

number. Each bit identifies a capability of the multiplexer. The following bits are
defined:
2-0: Host interface type, 0 = serial, 1 = USB, 2 = Ethernet, 3 = USB
3: SeaTalk1 transmission supported
4: NMEA 2000 supported
15-13: Multiplexer generation: 5 = 4th generation

hh: checksum

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Technical Specifications

MiniPlex-3USB

Supply voltage: 8 – 35 VDC, protected against reversed polarity.

Current consumption: 50 mA (100 mA max. with fully loaded talker ports)

Host interface: USB, galvanically isolated

Inputs: 4 x NMEA 0183/RS-422, galvanically isolated. Input 1 can be set to

SeaTalk mode

Input resistance: >1.4 kOhm

Input current: 0.5mA @ 2V

3.0mA @ 5V

7.1mA @ 10V

Outputs: 2 x NMEA 0183/RS-422, galvanically isolated.

Max output current: 20mA @ >2V

Queue size: 1024 characters

Filter list size: 50 sentence types

Priority list size: 50 sentence types

Speed NMEA In 1-3: 4800 - 57600 Baud

Speed NMEA In 4/Out 1: 4800 - 57600 Baud

Speed NMEA Out 2: 4800 - 115200 Baud

Indicators: Overflow and Data

Dimensions: 138 x 72 x 33 mm

Housing: Flame retardant ABS.

MiniPlex-3USB-N2K

NMEA 2000 Port: LEN: 1

Speed: 250kbps

Connector: M12 male Micro-C

59

MiniPlex-3E

Supply voltage: 8 – 35 VDC, protected against reversed polarity.

Current consumption: 100 mA (150 mA max. with fully loaded talker ports)

Host interface: 10BASE-T/100BASE-TX Ethernet

Supported protocols: TCP/IP and UDP, port 10110 for NMEA communication

TCP/IP, port 10110 for firmware updates
TCP/IP and UDP, port 30718 for network configuration
ARP, ICMP and DCHP for network management

Inputs: 4 x NMEA 0183/RS-422, galvanically isolated. Input 1 can be set to

SeaTalk mode

Input resistance: >1.4 kOhm

Input current: 0.5mA @ 2V

3.0mA @ 5V

7.1mA @ 10V

Outputs: 2 x NMEA 0183/RS-422, galvanically isolated.

Max output current: 20mA @ >2V

Queue size: 1024 characters

Filter list size: 50 sentence types

Priority list size: 50 sentence types

Speed NMEA In 1-3: 4800 - 57600 Baud

Speed NMEA In 4/Out 1: 4800 - 57600 Baud

Speed NMEA Out 2: 4800 - 115200 Baud

Indicators: Overflow and Data

Dimensions: 138 x 72 x 33 mm

Housing: Flame retardant ABS.

MiniPlex-3E-N2K

NMEA 2000 Port: LEN: 1

Speed: 250kbps

Connector: M12 male Micro-C